FY 2000 PROGRAMS AND ACCOMPLISHMENTS

National Institute of

Standards and Technology

Technology Administration

U. S. Department

of Commerce

NISTIR 6596
Advancements in Measurement Science 

Development and application of measurement methods is an integral part 

of the Polymers Division’s projects. Examples in process monitoring, 

combinatorial methods and neutron scattering are depicted on the cover.

Upper left composite 

On-line stroboscopic microscopy captures the action of processing 

 additives during the extrusion of polyethylene. The polyethylene is forced 

under the action of a twin-screw extruder (upper left of photo) through 

a sapphire tube (bright cube in center) and into the atmosphere (lower 

right of photo). The microscope objective is visible beneath the sapphire 

flow tube.

Lower Right composite

Advances in Process Visualization led to the discovery of “superstrings” in 

sheared polymer blends. When a blend of polymers droplets in a matrix of 

a second immiscible polymer is subject to a shearing action between two 

closely separated plates, there is a massive reorganization of the droplets 

into large stable strings.

Upper right composite

Direct visual image of the phase diagram of polystyrene and polyvinylmethylether obtained by depositing a composition gradient orthogonal to 

a temperature gradient. Data from conventional measurements are shown 

as open circles. A special apparatus, shown below the visual phase 

 diagram, was constructed to prepare films with gradient compositions 

and/or thickness by a computer controlled flow coating procedure. Film 

thickness and composition contours of dried films are mapped using a 

spot ellipsometer and infrared spectroscopy, respectively.

Lower left composite

Scanning electron micrograph and small angle neutron scattering pattern 

of a 700 nm thick photoresist film with 150 nm lines. Neutron scattering 

is explored as a method to quantify lithographic patterns of finer size 

scales in response to metrology needs of the semiconductor industry as it 

develops higher speed IC chips. 
UNITED STATES 

DEPARTMENT OF

COMMERCE

Donald L. Evans, 

Secretary

TECHNOLOGY

ADMINISTRATION

Karen H Brown, 

Acting Under Secretary of 

Commerce for Technology

NATIONAL 

INSTITUTE OF

STANDARDS AND 

TECHNOLOGY

Karen H. Brown, 

Acting Director

MATERIALS

SCIENCE AND

ENGINEERING

LABORATORY

POLYMERS

FY 2000 PROGRAMS 

AND

ACCOMPLISHMENTS

Eric J. Amis, Chief

Bruno M. Fanconi, Deputy

NISTIR 6596

January 2001

ME

UNITED STATES OF AMERICA

DEPARTMENT OF COM RCE
iii

TABLE OF CONTENTS 

Executive Summary ---------------------------------------------------------------------------------------------- 1

Technical Activities 

Accomplishments, Impacts And Recognition 

Off-Shore Oil Industry Benefits From New Tools for Design of Composite Structures -------------------------- 3

Fluorescence Based Temperature Measurements Impact Industrial Polymer Processing ------------------------- 5

New Tools In The Battle Against The “Sharkskin” Instability In Polymer Extrusion ---------------------------- 7

Polymer Reference Materials for Calibration of Instruments and for Benchmarking ---------------------------- 9

Nitric Acid-Modified N-Phenyliminodiacetic Acid – A Total Self-Etching Primer for Bonding to Tooth 

Structure ------------------------------------------------------------------------------------------------------ 11

Combinatorial Measurements of Phase Separation and Dewetting in Polymer Films ---------------------------- 13

Structure and Property Measurements of Porous Low-k Dielectric Thin Films ---------------------------------- 15

Polymer Composite Dielectrics Enable Development Of Embedded Decoupling Capacitance Technology For 

High Speed Electronics ---------------------------------------------------------------------------------------- 17

Projects and Programs 

Combinatorial Methods -------------------------------------------------------------------------------------------- 20

Combinatorial Study of Surface Patterns in Thin Block Copolymer Films -------------------------------------- 21

High-Throughput Measurements of the Film Properties of a Crystalline- Amorphous Polymer Blend ----------- 22

Pattern Formation in the Crystallization of Polymer Blend Films ----------------------------------------------- 23

Polymeric Templates for Combinatorial Assay of Cellular Reception ------------------------------------------- 24

Twin-screw Extrusion of Biocompatible Polymers for Tissue Engineering ------------------------------------- 25

Polymeric Substrates for Laser Capture Microdissection (LCM) ----------------------------------------------- 26

Dental And Medical Materials Program 28

A Moldable, Resorbable, Macroporous, Composite Bone Graft Containing Growth Factor --------------------- 29

Bioactive Polymeric Composites for Mineralized Tissue Regeneration ----------------------------------------- 30

Structure-Property Relationships in Dental Polymers ----------------------------------------------------------- 31

Materials For Microelectronics Program ------------------------------------------------------------------------ 32

Photolithography ---------------------------------------------------------------------------------------------- 33

Permittivity of Polymer Films in the Microwave Range -------------------------------------------------------- 34

Characterization of Porous Low-k Dielectric Constant Thin Films --------------------------------------------- 35

Measurement of In-Plane CTE and Modulus of Polymer Thin Films ------------------------------------------- 36

Electronic Paper ----------------------------------------------------------------------------------------------- 37

Hygrothermal Expansion of Polymer Thin Films --------------------------------------------------------------- 38

Assembly of IC Chips Using Wafer-Level Underfill ----------------------------------------------------------- 39

Multiphase Polymeric Materials Program ---------------------------------------------------------------------- m 40

Constitutive Relationship of Polymer Blends for Process Modeling Needs ------------------------------------- 41

Characterization and Modeling of Interfaces and Interphases of Polymeric Systems ---------------------------- 42
iv

Synergistic Interactions Of Polymers With High Surface Area Nanofillers ------------------------------------- 43

Mechanics of Fiber and Nano-Filled Composites -------------------------------------------------------------- 44

Structure-Property Characterization and Modeling ------------------------------------------------------------- 45

Modification of the Phase Stability of Polymer Blends by Filler Additive -------------------------------------- 46

Nanofiller-Induced Suppression of Dewetting in Thin Polymer Films ------------------------------------------ 47

Polymer Characterization Program ------------------------------------------------------------------------------ 48

Optical Coherence Tomography for Material Characterization ------------------------------------------------- 49

Advanced Metrology for Surface and Interface Chemical Analysis --------------------------------------------- 50

Molecular Mass Distribution of Polymers by Mass Spectrometry ----------------------------------------------- 51

Standard Test Method Development --------------------------------------------------------------------------- 52

Non-Newtonian Standard Reference Materials for Rheology --------------------------------------------------- 53

Support for the Biomaterials Integrated Products Industries ---------------------------------------------------- 54

Semicrystalline Polymer Structure by Small Angle Scattering -------------------------------------------------- 55

Partitioning of Chain Defects in Isotactic Polypropylene ------------------------------------------------------- 56

Morphology of Ultra-thin Films of Semi-crystalline Polymers by TEM ---------------------------------------- 57

NMR Characterization of Nylon-6/Clay Nanocomposites ------------------------------------------------------ 58

Real-Time Monitoring of Biaxial Stretched Film --------------------------------------------------------------- 59

Extrusion Visualization Facility Sheds Light on Processing ---------------------------------------------------- 60

“Superstring” Structures During Micro-Scale Processing ------------------------------------------------------- 61

Interfaces in Fiber Reinforced Polymer Composites ------------------------------------------------------------ 62

Fiber Optic Flow and Cure Sensing for Liquid Composite Molding -------------------------------------------- 63

Publications -------------------------------------------------------------------------------------------------------- 64

Staff And Organizational Structure

Research Staff ------------------------------------------------------------------------------------------------- 76

NIST Organization Chart -------------------------------------------------------------------------------------- 85

MSEL Organization Chart ------------------------------------------------------------------------------------- 85

Polymers Division Organizational Chart ----------------------------------------------------------------------- 86

Certain commercial materials and equipment are identified in this report in order to specify adequately the experimental procedures. 

In no case does such identification imply recommendation or endorsement by the National Institute of Standards and technology 

(NIST) nor does it imply necessarily the best available for the purpose. 
Polymers Division

1

Executive Summary 

From electronics and health care to automotive, infrastructure, 

and consumer products, polymers (or "plastics" as the TV 

commercial says) are an increasing part of global economic 

growth of U.S. industry. The increasing role of polymeric 

materials in rapidly growing industrial markets, and as 

replacements for traditional materials, creates a particular 

challenge to our Division. We continue to evaluate our 

technical programs to respond to the measurement needs 

stimulated by new materials formulations and their innovative 

uses. Furthermore, the rapid pace of change demands new 

ways of serving our customers, both long-established and new. 

We continue to support our traditional customers, for example 

in the chemicals, processing, and automotive industries, at the 

same time as we strengthen our activities in electronics and 

health care. Likewise, as a measurements laboratory that 

continues to provide the data that "sets the standard" we are 

pioneering in areas of combinatorial methods, mass 

spectrometry, advanced scattering techniques, and new 

imaging methods in anticipation of future opportunities. 

The Division undertook a major structural reorganization 

during the past year in order to respond to a changing research 

environment and to anticipate evolving priorities. Similar to 

trends in academic centers and industrial laboratories our new 

organizational structure features teams that are formed and 

dissolved in response to needs and opportunities. 

Five research areas (Electronics Materials, Biomaterials, 

Multiphase Materials, Processing Characterization, and 

Combinatorial Methods) are identified as focused teams. For 

their highest priority projects these groups collaborate with 

people from across the Division. In addition to focused teams 

we staff a central Characterization and Measurement Group 

that is working to develop and extend measurement 

capabilities and develop reference materials. Across the 

Division there are many new examples of projects with time, 

facilities, and expertise shared between the groups. 

The style of the annual report is also different this year. The 

Division’s work is presented as project updates from continuing projects and reports on completed projects. These are 

grouped according to the Materials Science and Engineering 

Laboratory programs in which we participate, including 

Materials for Microelectronics, Multiphase Polymeric 

Materials, Dental and Medical Materials, Polymer Characterization, and Combinatorial Methods. At the beginning of the 

report we have also included special highlights of accomplishments from eight projects. The highlighted projects 

include the following. 

• In collaboration with the University of Houston, a 

computer model has been developed to predict vibration 

effects on composite drilling and production risers used 

by the offshore oil industry. We have provided new test 

methods and data to validate the modeling. 

• Our fluorescence based, spatially resolved temperature 

measurement was demonstrated on a complex reactive 

extrusion line in a Dow Chemicals Company plant. The 

tests identified an unknown and detrimental excursion 

above the resin degradation temperature that can arise 

from shear heating in the processing line. 

• The NIST Extrusion Visualization Facility was used in 

collaboration with 3M to watch the actions of polymer 

processing additives (PPA) as they are used to eliminate 

the processing defect known as sharkskin. We have 

provided the first quantitative measurement tools with 

which to gauge PPA performance. 

• We added three new polyethylene Standard Reference 

Materials this year. A total of six SRM’s from 6000 u to 

200,000 u are now available only from NIST. Virtually all 

U.S. manufacturers of polyethylene purchase NIST 

molecular mass standards. We have also released the first 

reference biomaterial, an orthopedic grade ultrahigh 

molecular weight polyethylene. 

Processing

Characterization Characterization Biomaterials

Electronics Electronics

Materials

Multiphase

Materials

Multivariant

Measurement

Methods Methods

Characterization Characterization

and and

Measurement Measurement
Executive Summary

2

• In collaboration with the American Dental Association 

Health Foundation we have filed a patent on a new selfetching primer that is applicable to both dentin and 

enamel with identical bond strength. This promises to 

provide a much less complex adhesive system for use by 

practicing dentists. 

• We have developed a unique approach to the application 

of combinatorial methodology for investigation of 

polymer thin films and coatings. This work has demonstrated the promise of a rapid, broad-based, generalizable 

approach to high-throughput measurements in polymer 

materials science. 

• We have developed novel methodology for on-wafer 

measurements of the physical and structural properties of 

porous thin films that are being developed for use as lowk dielectric materials in the semiconductor industry. The 

NIST measurements are providing the standard for 

comparison of all other techniques. 

Although this has been a year of transitions for the Division, it 

has also been a very productive year. We continue to attract 

excellent scientists from the U.S. and internationally as guest 

researchers. In the 2000 competition, eight new National 

Research Council postdoctoral associates joined the Division. 

We continue to produce world-class research with another 

increase in technical publications to a total of 175 from the 

Division in FY2000. We extend the reach of our work by 

presentations at a broad range of venues. 

Across the board we have high expectations founded in a long 

history of impressive accomplishments. As we look forward to 

the NIST Centennial year of 2001, we know that the Polymers 

Division will continue to achieve excellence, and we strive 

with enthusiasm to be the best laboratory in the world for 

fundamental measurements in polymer science. 

Eric J. Amis 

Chief 
Data validates new design tools 

3

Off-Shore Oil Industry Benefits From New Tools for Shore Oil Industry Benefits From New Tools for 

Design of Composite Structures Design of Composite Structures

The off-shore oil industry needs the light weight of composite structures if it is to retrieve the vast supply of oil that exists in deep 

water deposits. In the last five years, fabricators have make composite components such as drilling and production risers, but

their light weight can magnify problems such as harmful vibrations induced by waves and currents. A joint program between 

NIST and the University of Houston has provided the first tools that allow industry to simultaneously optimize material selection

and structural design to control unwanted vibrations in drilling and production risers. The basic material property data are 

generated by NIST and used in a computer model developed by the University of Houston to predict vortex-induced vibrations so 

the effects of changes in material and design can be determined. 

Many industries are seeking to take advantage of the weight 

reductions that can be achieved by replacing metal 

components and structures with polymer composites. 

Although this substitution is often successful, one 

complication that can arise is a change in dynamic response 

of the structure. In some cases this can be advantageous, as 

has been found for certain drive shaft applications, but in 

other instances the changes may cause problems. Unlike 

metals, however, composites have excellent damping 

properties that can be used to help control any unwanted 

vibrations produced by external dynamic loading. Moreover, 

the great flexibility available in composite structures through 

changing both materials and designs can be used to alter 

damping and resonance properties in desirable ways. To take 

advantage of this flexibility, however, requires a model that 

predicts behavior of the structure from the properties of the 

constituents and the design, data on properties of the 

constituent materials, and knowledge of how these properties 

relate to the material’s composition and morphology. 

An important example of this general problem occurs in offshore oil drilling. The U.S. needs to reduce its dependence 

on foreign oil and most of the known reserves are in deep 

water (below 600 m). The light weight of composite 

structures is critical for industry to build drilling and 

production risers that can reach these depths. Industry has 

developed the technology to make risers, but calculations 

show that the reduced weight shifts the dynamic response of 

the structure into a range where interactions with currents and 

waves could be a problem. This dynamic response of the 

riser is called vortex induced vibration (VIV), and a 

commercial software program is used to analyze VIV in riser 

design. Unlike metal risers, however, composite structures 

have material damping capability that can counteract 

problems related to VIV. Unfortunately, the currently 

available software program does not have the capability to 

include material damping since it is not a factor with metal 

structures. 

NIST and the University of Houston have addressed this 

issue as part of a joint program on composite structures. The 

University of Houston has developed an analysis code that 

Diagram of off-shore oil platform showing risers 

can predict vibrational motions in drilling or production risers 

from a knowledge of design and material properties. NIST 

has utilized its capabilities to characterize the dynamic 

mechanical behavior of various resins systems since they are 

the source of damping in a composite structure. For the VIV 

analysis, material property data are needed over a relatively 

modest range of parameters. For example, the frequencies of 

interest extend from 0.001 Hz to 20 Hz. In order to improve 

the response of a material or select a better material, however, 

it is essential that the behavior be understood in terms of 

molecular structure and morphology. This requires a 

knowledge of properties over a much wider range of 
for the off-shore oil production industry 

4

parameters. Fortunately, time-temperature superposition can often be applied to the data so results over a wide range of 

frequencies can be obtained. This is illustrated in the figure below where the overlapping points are data generated by NIST

for the resin system now being considered for use in risers. By superimposing data at various temperatures, a master curve was

generated that predicts the behavior over a wide range of frequencies. This curve shows that the damping in the range of interest 

for risers can be attributed to the tail of the tan δ peak, which is associated with the glass transition temperature, Tg. Based on 

this, we formulated and tested a second resin system (solid curves in the figure) that contained a small amount of an elastomeric

additive. The additive has some compatibility with the resin so in addition to creating a second phase, it also broadened the 

glass transition and the corresponding tan δ peak for the resin Tg. As a result, the damping in the range of interest is increased. 

When this resin system was used in the analysis of vibration for a riser, the behavior was significantly improved. 

Reference Temperature 95 o

C

Frequency (Hz)

10-11 10-9 10-7 10-5 10-3 10-1

Shear Modulus (MPa)

10

100

1000

tan (

δ)

0.01

0.1

1

Curves generated by time-temperature superposition for one of the resins currently being used in riser 

systems (overlapping points) and a second system which was modified to increase the damping (tan δ) in the 

range from 1 Hz to 10-4 Hz. 

This one example provides only a small glimpse of the possibilities available through proper formulation of the resin system. 

By varying the structure of the resin, the concentration of the additive, and the degree of phase separation, very large changes in 

the vibrational and damping behavior of the resin can be achieved. Consequently, the material can be designed to give 

outstanding performance in a riser. 

For More Information 

On This Topic 

S. S. Wang, J. G. Williams, and D. L. Hunston, “Composite Materials for Offshore 

Operations”, Proceedings of the Third International Workshop, NISTIR, 2001. 

Donald Hunston and Carl Schultheisz

Chevron, Conoco, and Halliburton, are among the companies with interest in a follow up program to 

explore optimizing vibrational behavior in risers structures.
A new temperature monitoring method 

5

Fluorescence Based Temperature Measurements 

Impact Industrial Polymer Processing 

Temperature is the most important parameter for controlling and modeling polymer processing. It plays a fundamental role in 

determining flow characteristics, degradation phenomenon, phase transitions, and morphology of the final product. Accurate 

measurements of resin temperature are not obtained using conventional methods such as thermocouples because such devices are 

unduly influenced by the large thermal mass of the processing machine. Resin and machine temperatures are never the same 

because the viscous resin dissipates energy during flow causing its temperature to increase significantly, sometimes approaching

the degradation threshold. Our method to measure the true resin temperature is based on fluorescence spectroscopy. The 

technique has implications for materials testing, for development of processing strategies and for process control. 

A new method for measuring temperature of a resin during 

processing has been developed. The technique addresses a 

long standing problem in polymer processing and materials 

testing to obtain accurate and true resin temperatures. 

Although measurements using thermocouples are the 

standard practice, it is well known that this measurement 

does not reflect the resin temperature because the device is 

unduly influenced by the large thermal mass of the 

processing machine. During processing, heat is dissipated in 

the resin by virtue of its own viscosity or by chemical 

reactions. Since temperature is the most important parameter 

for understanding and controlling the process, it must be 

measured accurately. 

The new method is based on fluorescence spectroscopy and 

uses a temperature sensitive fluorescent dye that is doped into 

the resin. Concentration of dye in resin on the order of a 

mass fraction of 10-6 dye is sufficient for using fluorescence 

spectra as a monitoring tool. When mixed with the resin at 

elevated temperatures, the dyes are soluble in the resin matrix 

so that the dye is completely surrounded by the resin at the 

molecular level. The concept regarding fluorescent dyes is 

that they are molecular probes, i.e., they respond to the 

molecular environment in which they exist and report 

conditions of the environment via their spectra. Thus, a 

fluorescence temperature is a true resin temperature. 

Sensor hardware for interfacing with polymer processing 

machines consists of optical fibers that are inserted into 

existing instrumentation ports in the machine. For example, 

the standard half-inch sensor bolt for thermocouple or 

pressure transducers can be adapted to receive optical fibers. 

The fibers are used to transmit excitation light to the resin, to 

collect the resultant fluorescence light, and to transmit it to 

the detector. The NIST sensor head has been fitted with 

confocal optics so that temperature profiles of a resin flow 

stream can be obtained. 

Two dyes we have used for process monitoring are perylene 

and benzoxazolyl stilbene (BOS). 

Temperature sensitivity of the dyes arises from the fact that 

probabilities of fluorescence decay from an excited state to 

different ground state energy levels are temperature 

dependent. This is illustrated in the spectral plot of 

polycarbonate doped with perylene. The data taken at 

various temperatures between 180 o

C and 295 oC display a 

continuous change in shape with increasing temperature. 

Polycarbonate/perylene

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05

3.0E+05

3.5E+05

420 440 460 480 500 520 540

Wavelength nm

Intensity (arbitrary units)

T = 180 oC

T = 295 oC

The fluorescence spectrum of the dopant die molecule is 

temperature sensitive. Its key spectral features are 

measured on-line during processing.

optical fiber cable

lens for

confocal design

sapphire window

optical sensor ports

focusing .

The optics is rugged and compact enough to fit into the 

standard extrusion instrumentation ports.
for the polymer processing industry 

6

An important application of the technology is temperature 

monitoring during reactive extrusion. The NIST confocal 

temperature sensor was positioned at the exit die of an 

extruder for this measurement. The standard uncertainty in 

the temperature data is ± 2 o

C. The higher temperatures at 

1.5 mm from the wall are due to a combination of shear 

heating and the exothermic chemical reaction. 

In another application of the confocal temperature sensor, a 

capillary rheometer was instrumented as shown below. Here, 

excitation light was focused on the extrudate, polyethylene 

doped with perylene. The objective is to obtain viscosity as a 

function of shear rate at a constant temperature. The test 

provides basic materials rheological data that are used by 

U. S. polymer processors, particularly injection molders, to 

simulate process flows. This is an important step in setting 

up a new process and the simulation requires accurate input 

data. But, in order to use the results from this test, the data 

must be corrected for shear heating effects that occur at high 

shear rates. A temperature correction has not been possible 

heretofore because an accurate temperature measuring 

method has not been available. The impact of these new 

findings and the NIST measuring technique will be to change 

materials testing protocols so that accurate rheological data 

are made available for applications such as simulation 

software and process modeling. 

Collaborations with Mobil Chemical, DOW Chemical and 

Datapoint Labs are yielding important information that is 

impacting on processing strategies and understanding. 

“Fluorescence based temperature measuring methods 

developed by NIST address a long standing problem for 

obtaining accurate resin temperatures during rheological 

characterization.”... Hubert Lobo, Datapoint Labs 

“Accurate measurements of resin temperature gradients 

during extrusion processing have not been possible in the 

extruder barrel until the development of the NIST 

fluorescence based method.”.......Walter Buzanowski, an 

Analytical Leader in the Analytical Sciences Lab of The Dow 

Chemical Company. 

For More Information 

On This Topic 

“Fluorescence Based Temperature Measurements and Applications to Real-Time 

Polymer Processing”, A. J. Bur and S. C. Roth, Proc. Soc. Plastics Eng. Annual 

Technical Mtg., May 2000. 

“Fluorescence Based Measurement of Temperature Profiles during Polymer 

Processing”, K. Migler and A. J. Bur, Polym. Eng. Sci. 38, 213 (1998). 

Anthony J. Bur and Kalman Migler

Temperature profiles during the reactive extrusion of a 

polyhydroxyl alkyl ether (PHAE) doped with BOS dye 

reveal new information about this process that can be 

used to avoid resin degradation and produce a higher 

quality product. 

Errors in viscometric data from failure to account for 

shear heating lead to inaccurate modeling of the extrusion 

and injection molding processes. At shear rates above 

1000 s-1, resin temperature was above degradation 

threshold. 
New visualization technology 

7

New tools in the battle against the “sharkskin” 

instability in polymer extrusion 

The throughput of widely used polyolefins is limited by a processing defect known as “sharkskin,” which is a flow instability that 

causes an undesirable surface roughness on the extruded polymer. Polymer processing additives (PPAs) are commonly used to 

eliminate sharkskin, and hence are an enabling technology for the polyolefin industry. However, the mechanism by which they 

work is unclear, hindering development of next generation additives. We developed a capillary rheo-optics technique to visualize 

how PPAs eliminate sharkskin. We successfully monitored the coating of the PPA onto the internal surface of the capillary die 

wall and also measured extraordinary levels of slippage between the PPA and the polyolefin. These results provide the first 

quantitative measurement tools with which to gauge PPA performance. 

A substantial effort to understand and overcome sharkskin has 

been underway since it was first reported over 40 years ago. 

Sharkskin is a surface roughness that occurs in the extrusion of 

certain polymers such as linear low density polyethylene. (See 

photograph below). In the 1960s, the accidental discovery that 

sharkskin could be reduced or eliminated by the incorporation 

of a fluoropolymer polymer processing additive (PPA) allowed 

processors to increase throughput, reduce energy consumption, 

and enhance processing quality. Since then, the use of 

fluoropolymer PPAs has become widespread in polyolefins; 

resin manufacturers often add it to their polymer resins as part 

of an additive package. It is conjectured that fluoropolymer 

additives migrate to the die surface where they lower the 

surface energy, allowing the polyolefin to slip at the wall. 

The sharkskin instability produces a surface roughness that 

limits the manufacturing rate in numerous applications. 

However, the study of polymer process additives is made 

difficult for two reasons. First, there are no available in-situ 

measurement tools. Thus, it is difficult to know whether a 

given additive migrates to the surface, and if so, does it induce 

slippage? Second, at a fundamental level the cause of 

sharkskin and the precise reason that fluoropolymer additives 

reduce it are still under debate. This lack of understanding of 

the mechanism makes it conceptually difficult to rationally 

design new materials. These difficulties then spill over into 

other areas such as manufacturing efficiency, development of 

new metallocene based polyolefins and expanding the usability 

of PPAs into new markets. 

Using the NIST extrusion visualization facility, we have 

made substantial progress in addressing the shortcomings of 

the traditional techniques. We utilize stroboscopic optical 

microscopy to visualize the polyethylene-fluoropolymer 

system as they are extruded through a transparent circular 

capillary die. In the close-up photograph of the capillary 

apparatus (below), the bright cube in the center surrounds a 

capillary tube that is held in place by the steel gland fittings 

behind it. This capillary apparatus is situated at the exit of a 

Haake torque rheometer with a co-rotating twin screw 

extruder attachment. The extruder melts, mixes, and then 

pumps the polymer through the capillary die. The molten 

extrudate strand is seen exiting the sapphire tube and 

traveling to the bottom right of the photograph. The 

microscope objective lens is below the bright cube. 

.

The extrusion visualization facility provided the critical 

tool to determine the cause of sharkskin in polyethylene. 
for the polyolefin industry 

8

Using the NIST extrusion visualization facility, we have 

made the following measurements that are relevant to the 

sharkskin and PPA problem: 

• Local shear rate 

• Extensional shear rate 

• Coating kinetics 

• Wall slip and polymer-polymer slippage 

We were the first to directly visualize the fluoropolymer as it 

coats the capillary wall upon addition of the PPA to the host 

polymer. In the following sequence, we first extrude the pure 

host polymer. Next, we extrude the host polymer plus the 

PPA at a mass fraction of 0.1%. The fluoropolymer coats 

the surface in a stripe pattern which is difficult to discern at 

first but becomes sharper with time (see video micro-graph 

below). The formation of this structure at the surface 

coincides with the disappearance of sharkskin from the 

extrudate. 

Understanding the structure of the fluoropolymer as it 

coats the internal die surface may lead to new additive 

formulations and processing strategies. 

A second contribution that the extrusion visualization facility 

makes to the study of sharkskin and PPA is in measurement 

of the change in velocity profile of the polymer as it travels 

through the tube. The presence of the PPA has a dramatic 

effect on this velocity profile. Before the PPA was added, 

the polymer obeyed what is known as the “stick boundary 

condition.” The figure at the bottom-right shows the 

velocity of the polymer from the center of a cylindrical tube 

“depth = 0” to the outer wall “depth = 0.8 mm.” The 

velocity of the polymer goes to zero at the capillary wall. In 

the absence of any PPA (red curve) the velocity is a 

maximum at the center and decreases to zero at the wall. 

In the presence of the PPA, the polymer velocity remains 

finite at the wall. Note the existence of two discontinuous 

blue points at the wall. The upper one corresponds to the 

LLDPE and the lower one corresponds to the PPA. This is 

the first direct evidence of polymer-polymer slippage. 

Flow velocimetry in the presence of the PPA then shows that 

slip occurs for all throughputs. This slip is observed to occur 

at the interface between the two polymers. The magnitude of 

the slip extrapolation length (§ 200 μm) indicates that these 

two polymers are fully disentangled. 

The capillary rheo-optics methodology is shown to be an 

important complement to traditional capillary rheology. By 

providing both flow velocimetry and high speed imaging, a 

coherent picture of the suppression of sharkskin by use of 

fluoropolymer PPAs emerges. In the absence of the PPA, we 

confirm that slip in the die is not observed and thus is not a 

necessary ingredient for sharkskin. Upon addition of PPA, 

we observe the coating process through direct imaging. We 

see that the PPA forms elongated structures in the flow 

direction. The formation of the PPA layer coincides with the 

disappearance of the sharkskin in the extrudate. 

These results are impacting industry by providing 

quantitative measurement tools and in-situ screening methods 

for understanding how PPAs reduce sharkskin. Future work 

will concern the mechanism by which sharkskin occurs, 

measurements of slippage, and an attempt to understand why 

different polymers behave so differently with respect to 

sharkskin formation. 

Direct velocimetry experiments are replacing rheological 

measurements that are laborious and contain inherent 

uncertainties. 

For More Information 

On This Topic 

Kalman B. Migler 

0

10

20

30

40

50

60

70

0 0.2 0.4 0.6 0.8 1

With PPA

No PPA

Velocity (mm/s)

Depth (mm)

Slip

n = 0.71

n = 0.52
Standard reference materials 

9

Polymer Reference Materials for Calibration of 

Instruments and for Benchmarking 

Standard reference materials and reference materials are issued to address needs of the producers, processors and users of 

polymers for calibration and for performance evaluation of instruments used in the control of the synthesis and processing of 

polymers as well as benchmarks for comparisons of measurement methods and development of new materials. Recently produced 

standard reference materials include polyethylene of narrow mass distribution certified for mass average molecular mass and 

intrinsic viscosity and a nonlinear fluid standard for rheological measurements. In addition, the first reference biomaterial, an 

orthopedic grade ultrahigh molecular weight polyethylene, was issued for use in development of improved test methods for wear 

and as a benchmark for development of improved materials. 

New Polyethylene Molecular Mass Standards 

Three new polyethylene standard reference materials were 

certified for mass average molecular mass by light scattering 

and intrinsic viscosity in 1,2,4 trichlorobenzene. The three 

narrow mass fractions, Mw/Mn=1.2, together with the three 

narrow fraction polyethylene standard reference materials 

that NIST already provides, make a total of six narrow 

fraction polyethylene SRMs certified for molecular mass 

averages. The mass standards cover the mass range from 

6000 u to 200,000 u. The polymer industry, analytical 

laboratories and university researchers use these unique 

standards primarily for calibration of gel permeation 

chromatographs, the principal instrument used for 

determination of the mass distribution of polymers. The 

figure displays the chromatograms of these six standards. 

The starting materials for all six of these standards were 

produced by fractionation of a whole linear polyethylene that 

is also available from NIST, SRM 1475. 

Polyethylene is the dominant commercial polymer in the United 

States and worldwide markets. High temperature (130 °C) size 

exclusion chromatography (SEC), although a relative method 

requiring calibration, is the most commonly used method to 

establish the molecular mass of these polymers. Yet, few SEC 

calibration standards are commercially available for calibration 

of high temperature SEC. Molecular mass fractions of low 

polydispersity, Mw/Mn, of less than 1.2 (Mw is the mass average 

molecular mass and Mn is the number average molecular mass), 

are the most useful materials for calibrating SEC. The NIST 

polyethylene standard reference materials, SRMs, are the only 

available narrow fractions of polyethylene. Prior to the 

availability of these standards, crude approximations had to be 

used in the calibration of gel permeation chromatographs for 

mass distribution measurements. 

Non-linear Fluid Standard for Rheological Measurements 

Non-Newtonian rheological standards are developed to 

exhibit the typical polymeric behaviors of shear thinning and 

normal stresses; these standards are also used for calibration 

of rheological instruments and for research into improved 

measurement methods. 

Polymer fluids, such as polymer melts and solutions, often do 

Virtually all U.S. manufacturers of polyethylene purchase 

NIST molecular mass standards for measurement assurance.

not follow the simple Newtonian ideal in their flow behavior, 

demonstrating shear-rate dependent viscosities and normal 

stresses. Such fluids see wide application in everyday life 

(injection molding, paints and coatings, food products, etc.), 

and the ability to measure and characterize their behavior 

accurately is very important to optimizing their processing 

conditions. Since there are a number of commonly used 

methods to measure the flow behavior of polymers, the new 

Standard Reference Material (SRM 2490) will provide a way 

for comparing the performance of different instruments, as 

well as providing tools for research into better methods of 

measuring the rheological properties of polymeric fluids. 

SRM 2490 is certified for the shear-rate dependence of 

viscosity and first normal stress difference at temperatures of 

0 °C, 25 °C and 50 °C. The linear viscoelastic responses are 

also certified, along with the temperature dependence of the 

shift factors. The new polymer solution, SRM 2490, 

supercedes the previous SRM 1490 Nonlinear Fluid 

Standard, which was composed of a high-molecular mass 

polyisobutylene dissolved in normal hexadecane. This 

standard fluid was found to have two problems: first, it 

showed evidence of loss of homogeneity on storage, and 

-10

0

10

20

30

40

50

16 18 20 22 24 26 28

Volume

DRI Signal

SRM2887

SRM2885

SRM2886

SRM1482

SRM1484

SRM1483
for the polymer industry 

10

second, the working range of the fluid was limited by the 

crystallization of the normal hexadecane, which has a melting 

point of 18 °C (64 °F). SRM 2490, on the other hand, 

consists of polyisobutylene (molecular mass of 

approximately 106

 g/mol) dissolved in 2,6,10,14-

tetramethylpentadecane. This solvent is a branched alkane of 

a slightly higher molecular mass than normal hexadecane; the 

branching prevents crystallization or vitrification down to at 

least –60 °C, and the higher molecular mass reduces the rate 

of evaporation as compared to normal hexadecane. SRM 

2490 will be used in an interlaboratory comparison involving 

over 20 laboratories, representing instrument manufacturers 

and users in industry and at universities. The interlaboratory 

comparison will provide information regarding the 

laboratory-to-laboratory variability in the measurements; the 

variability in the measurement of the first normal stress 

difference is of particular interest. 

Reference Biomaterial for Orthopedic Research 

Reference Material (RM) 8456, an orthopedic grade Ultra 

High Molecular Weight Polyethylene (UHMWPE), became 

available in October 2000. RM 8456 is intended primarily 

for use in mechanical characterization of material properties 

and laboratory-simulated performance of orthopedic joint 

replacement implants. The availability of this reference 

polyethylene is expected to aid in development of improved 

test methods and materials by providing a benchmark for 

comparisons. The need for this reference biomaterial was 

identified at a workshop on reference biomaterials held at 

NIST and its development was the result of collaboration 

among a materials supplier, the orthopedic research 

community and NIST. 

The material used to prepare RM 8456 was donated by Poly 

Hi Solidur, Inc., MediTECH Division, Fort Wayne, IN in a 

form similar to that from which many orthopedic components 

are machined: a cylindrical bar with nominal dimensions of 

7.62 cm (3 in) in diameter. Reference properties, reported as 

mean values with their expanded uncertainties, are Young's 

modulus, tensile yield strength, tensile ultimate strength, and 

tensile elongation-to-failure. These properties characterize 

the bar across the center 5.62 cm (2.21 in) of its diameter and 

down the entire bar length. Material beyond the central 5.62 

cm was found to differ significantly from that within. 

Twenty laboratories representing instrument manufacturers 

and users will join in an interlaboratory comparison using 

the NIST Nonlinear Fluid Standard. 

The NIST Orthopedics Research Consortium, whose member 

companies manufacture 80% of orthopedic total joint 

replacement products sold in the U.S., developed a new wear 

testing apparatus for accelerated screening of new materials 

without compromising the basic wear mechanisms that take 

place in the human body. 

For More 

Information 

On This Topic 

Charles Guttman – Polymer 

molecular mass standards 

Carl Schultheisz – Nonlinear fluid 

standard 

John Tesk – Reference biomaterials

Certification of the Relative Molecular Mass and the Limiting 

Viscosity of SRM 2885-7, NISTIR 6454, 6456, 6487. 

Standard Reference Materials: Non-Newtonian Fluids for 

Rheological Measurements, Proc. SPE ANTEC, Vol. 1, pp. 

1042-1046, Orlando, Fl, January 5, 2000. 

Biomaterials FORUM, Vol.22, #6, Nov-Dec, 2000. 

Shear Rate (s-1)

0.001 0.01 0.1 1 10 100

Viscosity (Pa s) or

First Normal Stress Difference (Pa)

1

10

100

1000

10000

N1 at 25 °C

SRM 2490: PIB/Pristane solution

0 °C

25 °C

50 °C
Novel, simplified adhesives 

11

Nitric Acid-Modified N-Phenyliminodiacetic Acid – A 

Total Self-etching Primer for Bonding to Tooth 

Structure

Dental manufacturers and practicing dentists need stable, simplified, self-etching primers that will simultaneously condition both 

dentin and enamel surfaces and also mediate effective bonding to these mineralized tissues. Such self-etching primers will overcome 

many of the problems of current dental adhesives, promote conservative dentistry and benefit the general public.

Current dental adhesives systems are characterized by the 

complexity of their compositions and bonding procedures. 

Bonding protocols for applying a variety of adhesive agents 

often are technique sensitive, labor intensive and multi-step in 

nature. In order to cleanse debris (smear layer) from the 

surfaces of prepared teeth and condition these substrates to 

accept adhesive agents, many dental adhesive systems use 

strongly acidic etchants, e.g., aqueous phosphoric acid. These 

aggressive conditioners have a propensity to over-etch 

mineralized tissues, especially dentin which is not as highly 

mineralized as enamel and, consequently, lacks the superior 

buffering capacity of the latter. Many bonding protocols 

require rinsing and drying of the conditioned surface. 

Conditioning dentin with strong acids removes the smear layer, 

demineralizes peritubular and intertubular dentin and creates a 

micro-porous surface into which adhesive agents can diffuse. 

However, these conditioners have the potential of also 

damaging subsurface dentin and reducing the strength and/or 

durability of the adhesive interface. 

Recent studies at NIST have shown that N-phenyliminodiacetic 

acid (PIDAA), a unique imino diacid of moderate acidity 

(pH=2.5) with excellent chelation potential for calcium, can be 

used as a dentin conditioner. Not only does PIDAA remove the 

smear layer and create a micro-porous surface without 

excessive demineralization or the need for aqueous rinsing, it 

also has the ability to prime the surface for effective interfacial 

polymerization. Thus, PIDAA combines several functions in 

one adhesive agent: substrate conditioning for infiltration and 

surface activation for polymerization. Several, simplified, twostep dentin bonding systems based on PIDAA have been 

developed. However, there is a need for a self-etching primer 

that is effective not only with dentin but also with enamel, that 

is a “total” self-etching primer. PIDAA itself is only 

marginally effective as a self-etching primer for enamel. In a 

recently completed study we have shown that the addition of 

small quantities of strong acids such as nitric acid to PIDAA 

solutions results in effective “total” self-etching primers. SEM 

analysis of enamel treated with PIDAA primers showed that 

effective surface etching occurred (See Figures 1 and 2). 

For assessing shear bond strength to bovine enamel and 

human dentin, a two-step bonding protocol was used: 

1) aqueous acetone (1:1 by mass ratio) solutions of PIDAA 

(6.4 %) and nitric acid (NA) at two concentrations (2.5 % or 

1.25 %) were applied to either bovine enamel or human 

dentin surfaces for either 30 s or 60 s, rinsed with distilled 

H2O and air dried. 2) Five coats of 20 % photoactivated 

PMGDM (a carboxylic acid containing monomer, 

pyromellitic glycerol dimethacrylate) in acetone, were then 

applied and light cured 20 s prior to placement of a 

photocurable composite (irradiation time=60 s). All % values 

represent mass fractions.

Shear Bond Strength (SBS) and Standard Deviation in 

MPa to Tooth Structure 

Ɣ Bovine Enamel 

Self-etching Primer Time (s) SBS (SD) 

PIDAA + 1.25 % NA 60 27.9 (9.6) 

PIDAA + 1.25 % NA 30 27.3 (8.5) 

PIDAA + 2.5 % NA 60 32.8 (6.1) 

PIDAA + 2.5 % NA 30 28.0 (6.5) 

Ɣ Human Dentin 

Self-etching Primer Time (s) SBS (SD) 

PIDAA (Control) 60 24.7 (8.4) 

PIDAA (Control) 30 24.6 (6.5) 

PIDAA + 1.25 % NA 60 28.1 (7.0) 

PIDAA + 1.25 % NA 30 27.3 (11.1) 

A two-way ANOVA (Į=0.05) indicated that there was no 

statistically significant interaction between application time 

and NA concentration (p=0.4 for enamel and p=0.74 for 

dentin). 
for dentistry 

12

Fig. 1. Enamel surface after a 30 s application of 2.5 % HNO3

in 6.4 % PIDAA acetone/H2O solution. Note: selective 

demineralization to expose the microstructure of the enamel 

prisms. 

Fig. 2. Dentin surface after a 30 s application of 2.5 % HNO3

in 6.4 % PIDAA acetone/H2O solution. Note: the smear layer 

is demineralized and the dentinal tubule orifices are exposed. 

For More Information 

On This Topic 

Antonucci JM, Bennett PA; Method and Composition for Promoting Improved Adhesion to 

Substrates. U.S. Patent 5,498,643, March 12, 1996; U.S. Patent 5,690,840, November 25, 

1997; U.S. Patent 5,756,560, May 26, 1998. 

Joseph M. Antonucci, Frederick C. Eichmiller and Gary E. Schumacher

Simplified dental bonding systems, equally effective on both dentin and enamel, are 

feasible with certain acid-modified PIDAA solutions. We now have developed a selfetching primer applicable to both dentin and enamel by adding small amounts of 

stronger acids such as nitric acid to PIDAA. The resultant bond strengths of composite 

to enamel and/or dentin were virtually equivalent. A joint patent application with the 

American Dental Association Health Foundation (ADAHF) has been filed covering 

this technology. Previous relevant NIST patents have been licensed by ADAHF and 

sublicensed by Caulk/Dentsply. 
Novel measurement method 

13

Combinatorial Measurements of Phase Separation 

and Dewetting in Polymer Films 

An understanding of the stability and homogeneity of thin polymer films on solid substrates has technological and scientific 

importance in applications ranging from coatings, dielectric layers, and lubricant surfaces to fundamental studies of polymer thin 

films. Dewetting and phase separation are two important and commonly occurring phenomena that can be used to control the 

morphology, topography and chemical composition heterogeneity of polymeric surfaces. These phenomena are influenced by a 

large number of factors that include both material properties as well as process variables, leading to a multidimensional 

parameter space that is difficult to explore by conventional experimental and analysis methods. The power of combinatorial 

methods for mapping out phase separation and dewetting in polymer thin films is demonstrated here. 

Introduction 

Due to successes in pharmaceuticals research, combinatorial 

and high-throughput methods for searching composition 

space have received increasing attention for the synthesis and 

discovery of new inorganic materials, catalysts, and organic 

polymers. Combinatorial methods can also allow rapid 

scanning of parameter space to make fundamental 

measurements and develop physical models for polymers. 

One limitation is the difficulty of preparing parallel libraries 

and performing high-throughput screening with conventional 

instrumentation and sample preparation techniques. 

We present combinatorial methods for measuring two 

important fundamental properties of polymer thin films: 

dewetting and phase behavior of blends. In each case library 

creation, high-throughput measurements, and informatics are 

used to generate combinatorial maps of wettability and phase 

behavior. The temperature and film thickness dependence of 

the dewetting behavior of polystyrene on silicon is evaluated 

in combinatorial libraries in which thickness and temperature 

are varied systematically. Automated scanning optical 

microscopy is used to determine the time-temperaturethickness superposition of dewetting kinetics and to observe 

transitions between film stability regimes. By a similar 

methodology, the phase boundary for a polystyrene / 

poly(vinylmethyl ether) blend film is observed with 

composition-temperature libraries. The combinatorial 

method is validated by comparison to previous results. In 

this procedure, the wafers are cleaned in a Piranha solution to 

grow a thin (§10 Å) layer consisting primarily of SiOx. The 

results show that high-throughput experimentation is useful 

not only for the discovery of new materials, but also for 

observation of fundamental materials properties. 

Experimental 

Library Creation. To investigate polymer thin film 

dewetting phenomena, we used sample libraries with 

orthogonal gradients in thickness (h) and temperature (T) to 

create a large database of dewetting information in a few 

hours of experiments. Thickness gradients were prepared on 

“Piranha-etched” silicon wafers (Polishing Corporation of 

America) with a velocity-gradient, knife-edge coating 

apparatus. A drop of polymer solution was spread over the 

substrate under an angled steel blade (5 degrees relative to 

substrate) at constant acceleration. The solvent dried within 

seconds of spreading, and resulted in a polymer film with a 

gradient in thickness. The initial and final thicknesses and 

the slope of the gradient were controlled with solution 

concentration, blade-substrate gap width, and spreading 

velocity and acceleration. The thickness profiles, measured 

with 0.5 mm diameter spot-ellipsometry, had power law or 

polynomial dependence on position on the wafer, depending 

on the flow conditions. Solutions with mass fractions of 2% 

and 5% polystyrene (Goodyear, Mw = 1900 g/mol, Mw/Mn 

= 1.19, where Mw and Mn are the mass and number average 

relative molecular masses) in toluene were used to prepare 

25 mm wide sample wafers. 

Our high-throughput method for studying polymer blend 

phase separation involves the creation of libraries with 

orthogonal gradients in blend composition and temperature. 

Three steps are involved in preparing composition gradient 

films: gradient mixing, deposition, and film spreading. Two 

syringe pumps introduce and withdraw polymer solutions to 

and from a mixing vial at rates I and W, respectively, where I 

= W = 1.7 mL/min. Pump I contained mass fraction PS = 

0.080 of polystyrene (PS, Mw = 96.4 kg/mol, Mw / Mn = 

1.01, Tosoh) in toluene. The vial was loaded with an initial 

2.0 mL of mass fraction 0.080 of poly(vinylmethyl ether) 

(PVME, Mw = 119 kg/mol, Mw/Mn = 2.5) in toluene from 

pump W. The infusion and withdrawal syringe pumps were 

started simultaneously while vigorously stirring the vial 

solution, and a third syringe, S, was used to manually extract 

solution from the vial. The rates I, W and S, the initial 

volume in the vial, and the sampling time control the end 

points and slope of the composition gradient, which has been 

verified in situ with FTIR spectroscopy. 

Next the gradient solution from the sample syringe is 

deposited as a thin 31 mm long stripe on the silicon substrate. 

The gradient stripe was quickly placed under a stationary 

knife edge of equal length. The gradient stripe was spread as 

a film, orthogonal to the composition gradient direction, for a 

distance of 40 mm with the flow coating procedure described 

above. After a few seconds most of the solvent evaporated, 

leaving behind a thin film with a gradient of polymer 

composition. 
for materials characterization 

14

High Throughput Screening 

Both the thickness (dewetting) and composition (phase 

behavior) gradient samples were annealed on a linear T 

gradient heating stage, over a large range of T values, 90  ̊C

< T < 160  ̊C. A CCD camera (Kodak ES1.0) coupled to an 

optical microscope (Nikon Optiphot 2) sent (1024 x 1024) 

pixel, 8 bit digitized images to a computer that also 

synchronized sample stage movement over a grid of T and h 

conditions using a robotic x,y translation stage. For 

quantitative analysis of images, we averaged the library T 

and h values over the image area. At the beginning of each 

time cycle, the translation stage returned to a home position 

to within ± 0.5 μm. In a typical experiment, the T-h-t 

dependence of dewetting structures was followed by 

collecting a 5 by 5 array of images every 5 min over a period 

of 2 h, for a total of 600 images. Optical microscope images 

and photographs capture the phase separation process as a 

function of T and φPS with average standard uncertainties of 

T = ± 1.5  ̊C and φPS = ± 0.006. 

Results and Discussion 

Figure 1 presents a photograph of a typical temperaturecomposition library after 2 h of annealing, in which the 

LCST phase boundary can be seen with the unaided eye as a 

diffuse curve. Cloud points measured with conventional 

light scattering are shown as discrete data points and agree 

well with the phase boundary observed on the library. The 

diffuse nature of the phase boundary reflects the natural 

dependence of the microstructure evolution rate on 

temperature and composition. Near the LCST boundary the 

microstructure size gradually approaches optical resolution 

limits (1 mm), giving the curve its diffuse appearance. 

Figure 1. Photograph of a combinatorial library showing 

LCST phase boundary for PS-PVME with validating data 

from conventional scattering cloud points. 

Figure 2. Composite image of overlapping optical 

micrographs (one square image is 6 mm on a side) of a 

temperature-thickness library used to study thin film 

dewetting. Bright regions are more dewet than dark regions. 

A wide range of structures (holes [D] and polygons [A]) and 

both metastable and unstable (capillary nucleated [B]) film 

regions are observed in this image. 

By using a combinatorial technique to prepare libraries in 

which the temperature and thickness are varied 

systematically and continuously, we have also measured the 

temperature-thickness-time dependence of dewetting 

structures, stability, and kinetics in a small number of 

experiments. Figure 2 presents a composite optical image of 

a typical T-h library that indicates different dewetted 

structures and growth rates as a function of T and h. The 

libraries are able to reproduce a wide range of dewetted 

structures observed with our own uniform control samples 

and in previous work of others for similar systems, validating 

our methodology. The method presented here is unique in its 

ability to rapidly identify fundamental trends in film stability, 

nucleation mechanisms, and dewetting kinetics over a wide 

range of parameter space. Delineating these effects early in a 

scientific study can lead to observations of novel regions of 

phase space for thin film phenomena and can be extremely 

useful in guiding detailed analysis with conventional onesample for one-measurement approaches. 

For More Information 

On This Topic 

J.C. Meredith, A. Karim, E.J. Amis, Macromolecules, 33, 5760 (2000).

Alamgir Karim and Eric Amis 

110

115

120

125

130

135

140

145

150

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

T (

oC)

φPS
Critical characterization data 

15

Structure and Property Measurements of Porous 

Low-k Dielectric Thin Films 

Low-k interlayer dielectric materials have been identified by the microelectronics industry as a critical factor to enable deep

submicron technology for the continued improvement of integrated circuits. NIST is working to provide the semiconductor 

industry with unique on-wafer measurements of the physical and structural properties of porous thin films important to their use

as low-k dielectric materials. We have developed a novel methodology utilizing several complementary experimental techniques 

to measure the average pore size, porosity, pore connectivity, film thickness, matrix material density, coefficient of thermal 

expansion, moisture uptake, and film composition of several classes of candidate porous thin film materials. 

As integrated circuit feature sizes continue to shrink, new 

low-k interlayer dielectric materials are needed to address 

problems with power consumption, signal propagation 

delays, and crosstalk between interconnects. One avenue to 

low-k dielectric materials is the introduction of nanometer 

scale pores into a solid film to lower its effective dielectric 

constant. However, the pore structure of these low-k 

dielectric materials strongly affects important material 

properties other than the dielectric constant such as 

mechanical strength, moisture uptake, coefficient of thermal 

expansion, and adhesion to different substrates. The 

characterization of the pore structure is needed by materials 

engineers to help optimize and develop future low-k 

materials and processes. Currently, there is no clear 

consensus among IC chip manufacturers for the selection of a 

class of material or a processing method of nanoporous films. 

Candidates include silica-based films, organic polymers, 

inorganic spin-on materials, chemical vapor deposited 

materials, and several others. With the large number of 

possible materials and processes, there is a strong need for 

high quality structural data to help understand correlations 

between processing conditions and the resulting physical 

properties. 

The characterization of the pore structure of thin nanoporous 

low-k dielectric films is not straightforward. The small 

sample volume of 1 μm films and the desire to characterize 

the film structure on silicon wafers narrows the number of 

available measurement methods. We have developed a novel 

combination of small angle neutron scattering (SANS), highresolution x-ray reflectivity (HRXR), and ion scattering 

techniques to determine important structural and physical 

property information about thin porous films less than 1 μm

thick. These measurements are performed directly on films 

supported on silicon substrates so that processing effects can 

be investigated. HRXR is used to accurately measure the 

film thickness, the average film electron density, and the 

coefficient of thermal expansion. SANS is used to determine 

the pore structure, providing information such as the average 

pore size, pore connectivity, and moisture absorption. Ion 

scattering techniques are used to determine the elemental 

composition of the films. 

Important Properties:

• average pore size

• porosity

• matrix density

• pore connectivity

• moisture uptake

• coefficient of thermal expansion

1 μm

Schematic diagram of a porous thin film stucture for 

low-k dielectric material.

By combining information from all three of these techniques, 

we provided the first independent measurements of important 

quantities such as the film porosity and the pore wall density. 

By measuring the properties of a wide range of materials and 

processing conditions, the U.S. microelectronics industry is 

assisted in development of the proper materials and 

processing conditions for low-k dielectrics needed for the 

commercial production of next generation integrated circuits. 

During the past year, measurement efforts have been focused 

into three areas, characterizing current industrially relevant 

materials through International SEMATECH, gaining 

fundamental understanding of different classes of material 

preparation, and conducting an international round robin 

comparison of different on-wafer measurement techniques. 

International SEMATECH, a consortium of microelectronics 

companies, has provided more than 25 separate samples for 

characterization by NIST including spin-on glass materials, 

films from chemical vapor deposition, and organic thin films. 

The structural information provided by NIST is placed into a 

master database, combining data from a variety of sources, 

detailing both the structural and material properties needed to 

evaluate candidate materials. The data have been extensively 

used by member companies to guide the development of lowk dielectric materials for integration into future devices. 
for the microelectronics packaging industry 

16

Photograph of the interior of the NIST high-resolution 

x-ray reflectometer with a silicon wafer with a low-k 

dielectric thin film. 

Additionally, we have collaborated with several groups to 

provide measurements to better understand fundamental 

scientific issues in general classes of sample processing 

methods. With Dow Corning Corporation, our measurement 

methodology was used to better understand the effect of 

cosolvent concentration on the film structure using a 

two-phase processing method based upon sol-gel techniques. 

With Sandia National Laboratories and the University of 

New Mexico, our methodology was applied to characterize 

the pore uniformity, average pore size, and matrix material 

density variations in porous silica thin films using surfactant 

templates. With Lucent Technologies, our methodology was 

used to determine the structure of porous thin films prepared 

using a novel polymer porogen approach. The pore structure 

was measured as a function of processing temperature, 

polymer loading concentration, and polymer architecture. By 

directly correlating the resulting film structure with 

controlled variation of processing variables, we help provide 

the fundamental understanding needed to improve these 

fabrication methods. 

0.1

1

10

100

I (cm-1)

8 9

0.01 2 3 4 5 6 7 8 90.1 2

q (Å-1)

 Spin-on Porous Silica

 CVD Deposited Film

 Surfactant-templated Porous Silica

Representative small angle neutron scattering data from 

three different types of porous low-k dielectric thin films. 

Finally, we have established an international collaboration 

including private, government, university, and corporate 

research groups from NIST, IMEC (Europe), the Institute of 

Semiconductor Physics (Novosibirsk), the University of 

Michigan-Ann Arbor, the Kyushu Institute of Technology, 

CCIC, Ltd. in Japan, and Dow Corning Corporation to 

critically compare data from several different on-wafer 

measurement methods for the structure of porous thin films. 

The techniques, including the NIST methodology, 

ellipsometric porosimetry, and positron annihilation lifetime 

spectroscopy, are used to determine average pore size, film 

porosity, pore connectivity, pore wall density, and the pore 

size distribution. Each measurement method determines the 

film structure differently and provides complementary 

information. It is expected that the results from this 

collaboration will provide a needed overview and practical 

guidelines for researchers to rigorously characterize the 

structure of porous low-k dielectrics. The broad scope of this 

collaboration also provides extremely valuable information to 

the microelectronics industry for the selection of appropriate 

characterization methods to optimize measurement turnover 

rates and quality of data. 

For More Information 

On This Topic 

E. K. Lin, W.L. Wu, C. Jin and J. T. Wetzel, “Structure and Property Characterization 

of Porous Low-k Dielectric Constant Thin Films Using X-ray Reflectivity and Small 

Angle Neutron Scattering,” Mat. Res. Soc. Proc., San Francisco, CA, 2000, in press. 

Eric K. Lin, Barry J. Bauer, Wen-li Wu
New measurement method 

17

Polymer composite dielectrics enable development 

of embedded decoupling capacitance technology for 

high speed electronics 

Increased signal speed within electronic circuits can be achieved by creating an efficient local power supply for charging fast

processors and switching devices. Current technologies utilize surface mount discrete capacitors, which become ineffective at 

frequencies approaching 1 GHz. Our effort focused on embedded capacitance layers made of polymer composite films to 

effectively eliminate the switching noise. We have developed a specialized test vehicle design and invented a new testing 

procedure to verify the efficiency of embedded capacitance on circuit boards and to measure the broad-band dielectric 

permittivity of new materials at functional frequencies from 100 MHz to 10 GHz. 

High dielectric constant polymer composite materials are 

being developed by the electronics industry in response to the 

need for power-ground decoupling to secure integrity of high 

speed signals and reduce EMI radiated noise. Current 

technologies utilize surface mounted discrete chip capacitors, 

which can extinguish the power-bus noise at frequencies 

below 10 MHz. At higher frequencies, between 10 MHz and 

100 MHz, only capacitors with the lowest connection 

inductance are able to source the charge. As the operating 

frequency increases above several hundred MHz, all the 

discrete capacitors become ineffective. In response to these 

inherent problems NCMS, together with NIST and more than 

dozen partners, organized a collaborative research 

consortium aimed at developing and advancing the use of 

embedded-decoupling-capacitance (EDC) technology. The 

consortium identified a need to assess the feasibility of this 

design and to measure the materials dielectric characteristics 

at frequencies above 1 GHz. 

We have developed a specialized test technique to measure 

the dielectric permittivity of high dielectric constant films in 

the microwave range using a microstrip test vehicle shown in 

Fig. 1. The test vehicle comprises a two-layer circuitry and 

contains a number of microstrip resonators. To improve the 

accuracy of the measurements, we added to the test pattern 

appropriate non-coaxial terminations for in-situ calibration. 

The test pattern is appropriate for testing permittivity in the 

functional planar configuration of films, 10 μm to 50 μm 

thick having the dielectric constant ranging from 4 to 40 at 

frequencies from 100 MHz to 12 GHz. This frequency range 

is not covered by the existing standard test methods. 

The microstrip-resonator technique, which we developed and 

transferred to the industrial partners, allows for evaluation of 

permittivity of EDC films at discrete resonant frequencies 

that do not necessarily overlap with the dielectric relaxation 

process. In order to address the structural/dielectric attributes 

in adequate detail, broadband dielectric measurements are 

needed. However, the existing test procedures for thin films 

are based on lumped element approximations, which fail to 

produce meaningful results at microwave frequencies, 

especially in the case of high-dielectric constant films. 

We have recently achieved a breakthrough in broadband 

permittivity measurements of dielectric films in coaxial 

configuration and were able to extended the measurements to 

frequencies of practical importance, above 1 GHz (Fig. 2.). 

This has been accomplished by employing an appropriate 

theoretical model for the wave propagation in the specimen 

section. Neglecting the propagation, which is the current 

approach, leads to large systematic errors at microwave 

frequencies. 

We have determined that, contrary to the commonly accepted 

simplification, the propagation direction takes place along the 

diameter of the specimen rather than across the thickness of 

the dielectric.

Furthermore, we found that the limitations of the lumped 

element method originate from singular behavior at the halfwavelength resonance frequency which is determined by the 

diameter of the film specimen and its complex permittivity. 

The experimental permittivity results obtained in the broad 

frequency range compared very well with the microstrip 

resonance data at frequencies from 100 MHz to 10 GHz. 

The thin film configuration does not compromise the dielectric 

Fig. 1.Permittivity measurements of high-k films using 

microstrip test vehicle 
for the microelectronics industry 

18

loss measurements since the propagation length is 

independent of the specimen thickness. 

Fig. 2. Broad-band high frequency permittivity 

measurements of high dielectric constant films – comparison 

of the NIST developed technique with the prior approach. 

To the best of our knowledge, this data analysis scheme has 

not been successfully implemented before. 

We evaluated the microwave dielectric properties of several 

polymer-ferroelectric ceramic composites newly developed 

by the industry for EDC applications: BC2000 and 

EmCap from PolyClad, CPly from 3M and HiK

Polyimide from DuPont. The EDC materials measured in a 

functional test vehicle configuration showed an exceptionally 

low and flat impedance characteristic, indicating a much 

lower Q factor than could be expected from the dielectric 

properties of the organic and ceramic constituents. 

Our study discovered a high frequency relaxation behavior 

which is intrinsic to binary mixtures of organic polymer 

resins loaded with ferroelectric powders. We found that the 

position of the loss peak is determined by the dielectric 

relaxation of the polymer backbone while its magnitude 

depends on the dielectric dispersion, and therefore, is 

amplified by the content and permittivity of the ferroelectric 

component. 

We have recently started developing a new method for broadband impedance characterization of high-k films directly in 

the time domain. Experiments were conducted in a coaxial 

configuration to eliminate radiation effects, apparent 

dispersive behavior, coupling errors and inductive delays. 

This allowed us to monitor the response to a 12.5 ps rise time 

voltage step in a 10 ns time window with 2.5 ps resolution. 

Such resolution and fast responsiveness is essential for the 

proper evaluation of low impedance circuits. In comparison, 

other testing configuration that utilize coaxial connectors or 

coupling probes introduce inductive components that 

increase the system impedance well above that of measured 

impedance and therefore, limits the measurement range to 

slow responses only. It was found that at the time referenced 

to the incident voltage step Vi (time zero or at highest 

frequencies) all the EDC specimens appeared as a short 

circuit indicating a pure capacitive behavior. The best 

performance, indicated by the response close to that of zero 

impedance (short) termination, was observed for several 

industrial test materials. To our knowledge these results 

represent the most accurate experimental characterization of 

low impedance planes to date. 

We showed that polymer composite films filled with 

ferroelectric ceramics can provide low impedance through a 

high capacitance. In addition, such materials can also 

suppress the undesirable resonant behavior because of their 

intrinsic high loss. This makes polymer composites films 

attractive as a broad-band embedded de-coupling capacitance 

to secure the signal integrity and minimize the EMI noise in 

high-speed circuits operating at microwave frequencies. 

For More Information 

On This Topic 

J. Obrzut and C. K. Chiang, “ Dielectric measurements of embedded capacitance 

materials “ Embedded Decoupling Capacitance Project, NCMS Technical Report 

No.: 091RE00 August 20000, NCMS, 3025 Boardwalk, Ann Arbor, MI 48108. 

http://www.ncms.org/index.html. 

J. Obrzut, R. Nozaki 
19
Combinatorial Methods

20

Combinatorial Methods 

The Combinatorial Methods Program develops new 

measurement techniques and experimental strategies needed 

for rapid acquisition and analysis of physical and chemical 

data of materials by industrial and research communities. A 

multi-disciplinary, multi-OU team from the Measurements 

and Standards Laboratories of NIST participates to address 

key mission driven objectives in this new field, including 

assuring needed measurement infrastructure, expanded 

capability, standards and evaluated data. 

Measurement tools and techniques are developed to prepare 

and characterize materials over a controlled range of physical 

and chemical properties on a miniaturized scale with high 

degree of automation and parallelization. Combinatorial 

approaches are used to validate measurement methods and 

predictive models when applied to small sample sizes. All 

aspects of the combinatorial process from sample “library” 

design and library preparation to high-throughput assay and 

analysis are integrated through the combinatorial informatics 

cycle for iterative refinement of measurements. The 

applicability of combinatorial methods to new materials and 

research problems is demonstrated to provide scientific 

credibility for this new R&D paradigm. One anticipated 

measure of the success of the program would be more 

efficient output of traditional NIST products of reference 

materials and data. 

Through a set of cross-NIST collaborations in current 

research areas, we are working to establish the infrastructure 

that would serve as a basis for a broader effort in 

combinatorial research. Within MSEL, novel and elegant 

methods for combinatorial library preparation of polymer 

coatings have been designed to encompass variations of 

diverse physical and chemical properties, such as 

composition, coating thickness, processing temperature, 

surface texture and patterning. Vast amounts of data are 

generated in a few hours that help to understand how these 

variables affect material properties, such as coatings 

wettability or phase miscibility. Additional focus areas for 

both organic and inorganic materials include multiphase 

materials, electronic materials, biomaterials assay, and 

materials structure and properties characterization. State of 

the art on-line data analysis tools, process control 

methodology and data analysis methods are being developed 

as part of the program. 

In order to promote communication and technology transfer 

with a wide range of industrial partners, an industry-National 

laboratories-university combinatorial methods center is being 

organized by MSEL. The consortium will facilitate direct 

interactions on combinatorial measurement problems of 

broad industrial interest and efficient transfer of the methods 

developed to U.S. industry. 

Contact Information: Alamgir Karim 
Combinatorial Methods

21

Combinatorial Study of 

Surface Patterns in Thin 

Block Copolymer Films 

Alamgir Karim 

Block copolymers are an important class of polymeric 

materials with large potential for commercial applications. 

For instance, their unique properties in melts, blends and 

solutions leads to their use as adhesives, emulsifying agents, 

thermoplastic elastomers, compatabilizers, etc. Here we 

investigate a well studied model block copolymer system using 

combinatorial methods and demonstrate the power of the 

method to extract new information and novel phenomena 

occurring in block copolymer thin films. 

Polymeric materials can exhibit marked differences in 

behavior relative to the bulk when used as thin films and the 

thickness can greatly affect phenomena such as dewetting, 

phase separation and ordering on surfaces. To investigate the 

effect of film thickness on polymer materials expeditiously, a 

solution flow coater has been developed to produce thin films 

having continuous gradients in thickness. The flow coater 

uses a knife-edge suspended above a substrate with a small 

amount of solution placed under the knife-edge. The 

substrate is driven at constant acceleration to produce a 

gradient in film thickness. The film thickness is measured 

using an automated UV-visible interferometer and a twodimensional map of the film thickness is obtained. Using this 

gradient a variety of polymer thin film physical properties 

can be investigated. 

Map showing the change in film thickness for a thin 

film produced by the flow coater. 

To demonstrate the power and utility of such a gradient film 

approach, the well-studied phenomenon of ordering of 

symmetric diblock copolymers on surfaces is investigated to 

validate the high-throughput methodology and to investigate 

new phenomena revealed by this type of measurement. In 

thin films of symmetric diblock copolymers, the substrate 

and air interfaces induce formation of lamella parallel to the 

surfaces due to the preferential interaction of one of the block 

components with respective substrate and air surface. It is 

generally believed that complete lamellae are formed when 

the total film thickness is equal to an integral multiple of the 

bulk lamellar thickness, Lo, and incomplete lamellae 

50 μm

Optical micrograph showing the addition of two 

lamella to a block copolymer film as the film thickness 

changes from 81 nm (left) to 117 nm (right). 

consisting of holes or islands are formed otherwise. We 

revisit this problem in substantial detail using the highthroughput approach afforded by the gradient films. The 

thickness dependence of the morphology is exploited for the 

experiments here. 

Thin film gradients of polystyrene-b-poly(methyl 

methacrylate) were prepared with the flow coater. The 

morphology observed progresses from smooth regions to 

islands to co-continuous to holes back to smooth. This trend 

repeats itself several times with changing film thickness. The 

island and holes morphologies reproduce those observed 

previously but the extended smooth regions and the cocontinuous areas are novel observations. The entire library 

was produced in significantly reduced time relative to 

conventional single thickness samples. The smooth regions 

are found to accommodate a 0.28 Lo change in thickness that 

was attributed to the increased surface chain density with 

increasing film thickness and subsequent stretching of the 

chains. In addition the co-continuous regions are located at 

0.41 Lo above the smooth regions indicating a preference for 

hole formation relative to island formation. 

The results presented here indicate that the combinatorial 

methodology can reveal new features even in well-studied 

problems. The thin film gradient allows for the rapid 

exploration of parameter space governing thin film properties 

and enhances the ability to characterize the properties of 

polymer thin films. 

Contributors 

and

Collaborators 

Archie P. Smith, Jack F. Douglas, Eric J. Amis, Alamgir Karim (Polymers 

Division, NIST) 

J. Carson Meredith (Georgia Tech) 

30

40

50

60

70

80

90

0 5 10 15 20 25 30 35

0

5

10

15

20

25

30 Film Thickness (nm)

X position (mm)

Y position (mm)
Combinatorial Methods

22

High-Throughput

Measurements of the Film 

Properties of a CrystallineAmorphous Polymer Blend 

Jack F. Douglas, A. Karim 

Factors controlling the crystallinity and morphology of semicrystalline-amorphous polymer blends are important in the 

design of polymeric materials with tailored properties. There 

is a need for a greater understanding of the mechanisms 

controlling the degree of crystallinity in these blends and the 

influence of crystallization on blend phase separation. We 

investigate the effect of temperature, composition and film 

thickness on amorphous/crystalline blend films in a highthroughput manner to determine the interrelations between 

processing conditions and blend film morphology. 

Many industrial applications require control of the 

morphology of thin polymer films. Film morphology depends 

on many factors: method of formation (dipping, evaporation, 

spin casting), tendency of film components to phase separate 

or dewet, the crystallization of film components, etc. 

Moreover, the morphology is characteristically sensitive to a 

number of factors (presence of polymer-solid and polymerair interfaces, topographic and chemical patterns on the solid 

substrate, filler particles and amphiphilic additives, flow and 

electric fields, temperature gradients, etc.) that perturb the 

phase separation of polymer blends or the phase ordering of 

semi-crystalline polymers. In previous work, we showed that 

the real space structure of polymer blend phase separation 

could be studied in considerable detail by forming nearly 

two-dimensional "symmetric" polymer films in which one of 

the polymer components segregates to both the solid 

substrate and the polymer-air boundaries. The difference in 

the surface tension between the blend components causes the 

film surface to buckle in response to phase separation within 

the film. This buckling provides a source of contrast in 

optical and AFM measurements, enabling high-resolution 

measurements of the dynamics of the ordering process in real 

space. The phase separation patterns that form in these "ultrathin" blend films resemble simulated phase separation in twodimensions and these films thus provide a useful "laboratory" 

for studying fundamental aspects of bulk phase separation 

that are difficult to extract from bulk scattering 

measurements. Ultra-thin polymer films also have special 

features that derive from the thin film geometry (e.g., surface 

roughness varies with polymer composition, thickness and 

temperature) that are crucial for their applications. 

While previous studies focused on phase separation in thin 

films in relation to bulk phase separation, we investigate 

application-related property measurements in highthroughput manner. Since the parameter space is large 

(thickness, composition, temperature) we initially investigate 

each of these variables separately by forming films having a 

gradient in each variable. First, we prepare films having 

gradients in thickness that are relatively near-critical 

composition so that the phase separation morphology forms a 

labyrinthine “spinodal” surface pattern. We also manipulate 

the film morphology through a temperature gradient and 

determine the phase separation temperature (See figure). 

A blend of amorphous and semi-crystalline polymers (polymethyl methacrylate, PMMA/ polyethylene oxide, PEO) is 

shown in the figure. We continuously control the steady state 

pattern size through the variation of the film thickness. The 

pattern size varies linearly with film thickness in the ultrathin film regime. The film morphology also changes with the 

relative polymer composition and these films exhibit features 

not seen in amorphous-amorphous polymer blends. 

Controlling the morphology of thin polymer film coatings 

allows the film properties (friction, adhesion, optical 

properties, permeability) to be tuned. 

Contributors 

and

Collaborators 

V. Ferreiro, J. F. Douglas, E. J. Amis, A. Karim (Polymers Division, NIST) 

Composition 

 gradient

Temperature Gradient 

Thickness gradient

43 nm 52 nm 68 nm

79 nm 90 nm 101 nm

2 μm 2 μm 2 μm

2 μm 2 μm 2 μm
Combinatorial Methods

23

Pattern Formation in the 

Crystallization of Polymer 

Blend Films 

Jack Douglas, Alamgir Karim 

Polymeric materials often crystallize under non-equilibrium 

conditions and the optical and mechanical properties of these 

materials can depend strongly on the resulting crystallization 

morphology. An understanding of factors influencing crystal 

structure is then essential to controlling the properties of these 

materials. We find that an adjustment of the polymer composition 

in thin blend films allows the polymer crystallization patterns to be 

tuned through spherulitic, seaweed, symmetric and fractal 

dendritic forms. These patterns resemble phase field simulations of

solidification in alloy mixtures with a variable surface tension 

anisotropy, ε.

A competition between orderly and disorderly growth occurs in 

a wide range of pattern formation processes such as the growth 

of cell colonies, electrochemical deposition, etc. To better 

understand non-equilibrium pattern formation, and polymer 

crystallization in particular, it is important to have 

experimental and computational model systems that can be 

"tuned" through the recognized class of pattern types and to 

determine the interactions and processes that govern this type 

of pattern formation. 

The observation of general classes of non-equilibrium pattern 

formation has recently stimulated attempts to explain this 

"universality". Numerical and theoretical work has established 

the existence of crystallization "morphology diagrams", 

analogous to phase diagrams in materials at equilibrium. These 

theoretical advances provide a rationale for classifying 

crystallization patterns and insights into the origin of these 

patterns. 

Many recent experimental investigations of a variety of nonequilibrium pattern formation processes involving propagating 

wavefronts of increased "order" (spherulitic growth in a 

polymer crystallization context, dense branching or "seaweed" 

dendritic growth patterns, symmetric dendrite patterns as in 

snowflakes, and fractal dendritic structures) have also 

contributed to the developing classification scheme of nonequilibrium crystal growth. Pattern formation in nonequilibrium crystallization is predicted to depend on the degree 

of undercooling (or supersaturation) and a parameter governing 

the intensity of the expression of crystalline symmetry in the 

pattern formation, the surface tension anisotropy, ε. However, 

there have been no quantitative experimental investigations of 

crystallization in which ε is varied to verify the predictions of 

recent theories of non-equilibrium crystal growth and there is 

little understanding of factors that influence ε.

Polymeric materials have the advantage that the crystallization 

rate is usually much smaller than metals and small molecule 

liquids and it is often possible to obtain high supercooling in 

these materials. 

The crystallization of polymers can also accommodate large 

numbers of defects because of the chain connectivity so that 

introduction of impurities, defects due to irradiation, and 

other perturbations may be expected to influence ε and thus 

the gross crystallization morphology. 

Polymeric materials are then attractive as model systems for 

fundamental studies of non-equilibrium crystallization. A 

blend of a crystalline polymer (polyethylene oxide; PEO) and 

an amorphous polymer (polymethylmethacrylate; PMMA) 

was investigated in a thin film geometry. The blend films are 

sufficiently thin (thickness ≤ 200 nm) for phase separation to 

occur within the plane of the film. We find that the 

morphology of these blend films can be tuned through a 

variation of the blend and clay compositions and we compare 

these measurements to phase field simulations of a model 

liquid mixture in which the crystallization morphology can 

be similarly tuned through a range of pattern types. 

Contributors 

and

Collaborators 

V. Ferreiro, J. F. Douglas, A. Karim (Polymers Division, NIST) 

J. A. Warren (Metallurgy Division, NIST) 

ε = 0.01 ε = 0.002 ε = 0.012 ε = 0.05

Increasing surface tension anisotropy 

Increasing PEO/PMMA relative mass ratio 

Experimental Data- PEO/PMMA Blend Film 

Phase-Field Simulation-Alloy Mixture
Combinatorial Methods

24

Polymeric Templates for 

Combinatorial Assay of 

Cellular Reception 

Alamgir Karim, Eric J. Amis 

Surface structure is a key parameter for cellular response at 

the bio-interface. The use of polymeric biomaterials in 

implants and the biomedical industry relies on long-term 

favorable surface interaction for biocompatibility. We 

demonstrate the use of self-organization processes of dewetting 

and phase separation of thin polymer films to generate highly 

structured substrates that serve as unique polymeric platforms 

to assay cell growth and function. 

Novel high-throughput gradient methods have been 

developed to generate a range of surface structures by 

dewetting and phase separation on chemically patterned 

substrates. The research is motivated by an increasing 

awareness in the biomedical industry and the tissue culture 

community that surface interactions are critical in clinically 

relevant biocompatible materials. Surface topography and 

functionality are two of the key parameters that determine 

cell adhesion, expression, growth and phenotype. We utilize 

our knowledge of dewetting and phase separation on 

patterned substrates to efficiently generate topologically and 

functionally structured surfaces in a controlled manner. The 

high level of control is taken further by imposing a discrete 

step gradient in the pattern dimensions on the substrates that 

allow us to create a range of surface structures on a single 

substrate. The combinatoric approach enables us to address 

cell response in a systematic and realistic fashion. 

Poly(dimethylsiloxane) PDMS stamp used for soft 

lithography has 3 μm ridges with channel spacing 

ranging from 15 μm to 1 μm

The chemically patterned substrates were created by soft 

lithography, consisting of transfer of alkane-thiols on vapor 

deposited gold substrates by conformal contact of a 

poly(dimethylsiloxane) stamp. 

Topological surface structure was spontaneously generated 

by exploiting dewetting of thin polymer films. The surface 

morphology is sensitive to film thickness, spatial resolution, 

and the symmetry of the underlying chemical pattern. The 

step-gradient in the periodicity of the chemical pattern across 

the surface enables generation of a range of topologies, from 

structured droplet arrays, to ridges and undulating wave 

structures. The gradient in surface structure of model 

polymeric surfaces is being tested for rapid diagnosis of cell 

expression in a range of topographies. 

Droplet array of dewet PS on patterned substrate (6 μm). 

Pattern induced ridged topology in thicker films. 

Phase separation of a blend of poly (İ-caprolactone) (PCL) 

and poly (D-lactic acid) (PDLA) on the chemical pattern has 

also been determined to modulate surface functionality in 

stripes of hydrophilic and hydrophobic polymer. 

Contributors 

and

Collaborators 

Amit Sehgal, Alamgir Karim, Jack Douglas, Francis Wang, Carl Simon. Eric J. 

Amis (Polymers Division, NIST) 

Hoda Elgendy, Alessandro Tona (Biotechnology Division, NIST) 
Combinatorial Methods

25

Twin-screw Extrusion of 

Biocompatible Polymers 

for Tissue Engineering 

Newell Washburn, Alamgir Karim 

Porous polymeric scaffolds are currently being used in tissue 

engineering applications. Blending offers unique opportunities 

for combining biocompatibility of a restricted class of 

polymers with the mechanical strength of other polymers. We 

have demonstrated a new methodology for producing such 

materials using a traditional polymer processing technique, 

twin-screw extrusion. This method permits control over such 

important parameters as pore size and connectivity and was 

demonstrated to yield biocompatible materials. 

The field of tissue engineering is rapidly growing and there is 

a need for the development of methodologies to produce 

polymeric materials with specific properties. These include 

biocompatibility, mechanical integrity, appropriate surfaces 

to induce cell attachment, and a continuous porous structure 

with pores roughly the same size as the cells. The ideal 

processing technique would be amenable to large-scale 

production and not require the use of organic solvents that 

are difficult to remove and lead to cytotoxic responses from 

host tissue. We have focused on materials for orthopedic 

applications since this area is of particular current interest. 

Twin-screw extrusion is a commonly employed technique 

used to blend polymers. Two screws rotate in tandem inside a 

heated metal barrel that subjects the polymers to strong 

rotational and extensional flows, and leads to a finely mixed 

blend with domains on the order of a micrometer. The 

extruded material may be further processed and annealed at 

higher temperature that leads to coarsening of the domains 

and an increase in the characteristic length scale of the blend. 

In this work, poly(ε-caprolactone) (PCL) was blended with 

poly(ethylene oxide) (PEO) in a mini-compounder. PCL is a 

biocompatible polyester that has been widely used in 

biomedical applications and PEO is water soluble and nontoxic. The extruded blend was annealed for 20 min at 80 °C

and the PEO was subsequently dissolved, yielding a porous 

material shown below. This blend had a PEO volume fraction 

of 0.70 and is mostly void space after dissolution of PEO 

with water. 

The pores appear to form a continuous network, which is 

important for tissue development, and have a characteristic 

width of approximately 100 μm, which is considered optimal 

for cell growth. 

The mechanical properties were assessed by compression 

testing. A modulus of 1 MPa was observed at strains below 

20 % and a modulus of 10 MPa was observed at higher 

strains. 

The low-strain modulus is attributed to compression of the 

scaffold pores while the modulus at higher strains is closer to 

that of compact PCL. These values are consistent with the 

performance of scaffolds produced by other techniques. 

The biocompatibility of the extruded scaffold was assessed 

by seeding bone-producing cells, osteoblasts, on the material. 

The cells (top and right in figure below) appear to spread on 

the surface, indicating they are viable and the scaffolds are 

non-toxic. 

Contributors 

and

Collaborators 

Newell Washburn, Carl G. Simon, Jr., Alamgir Karim, Eric J. Amis (Polymers 

Division, NIST) 

Alessandro Tona, Hoda M. Elgendy (Biotechnology Division, NIST) 

Kimberlee Potter, Ferenc Horkay (NICHD, NIH) 

0.0 0.1 0.2 0.3 0.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Stress (MPa)

Strain
Combinatorial Methods

26

Polymeric Substrates for 

Laser Capture 

Microdissection (LCM) 

Alamgir Karim 

Laser Capture Microdissection (LCM), a novel technique 

recently developed at NIH for the Cancer Genome project 

utilizes fusible polymer thin films to capture single cancerous 

cells from frozen tissue. We demonstrate the possibility of 

augmenting the LCM instrumentation with capabilities for 

encapsulation of the captured cells in micro-wells and microchannels for in-situ analysis. With growing interest in microand nano-analysis, this extension with a set of tailor made 

micro-wells will enable bio-analysis of a single cell with 

dilution volumes of the order of pico- to femto-liters. 

Laser Capture Microdissection was conceived and developed 

at the National Institute of Health (NIH) for isolation and 

extraction of pure populations of target cells from a frozen 

tissue section. This simple technique facilitates further 

analysis without contamination from the surrounding tissue. 

The cells of interest are targeted microscopically through a 

polymeric transfer surface placed on the tissue. The film 

comprised of a proprietary ethylene-acrylate copolymer is 

chosen for its high coefficient of thermal expansion. A brief 

laser pulse fuses the film at the precise spot and focally 

adheres with the underlying cell(s) of choice. 

A schematic of the LCM enhanced micro-encapsulation 

tissue capture process.

Since the commercial introduction of LCM, in 1997, high 

levels of dilution in the aqueous media have often limited 

further analyses of extracted DNA, RNA, and proteins from 

the captured cells. This necessitates amplification of the 

analyte with the polymerase chain reaction (PCR) for further 

studies. Any cross contamination from healthy tissue 

introduces large variability in experimental observations. 

Microanalysis thus becomes imperative due to drastic 

reduction of the dilution volume for the captured cells. 

Micro-fabrication techniques using lithographic procedures 

have previously been used for creating arrays of microwells 

but have not been successfully adapted for application with 

LCM. 

We have demonstrated that the diode laser used in the 

existing instrumentation may be used to create thermally 

induced micro-wells in dye incorporated single or multi-layer 

smooth polymer films. The schematic also shows capture of 

the cell of interest from the tissue section (top focusing 

objective) in concert with creation of a microwell (bottom 

dye incorporated film). Complete spatial registry with the 

captured cells facilitates micro-encapsulation. 

The technique enables extension of the current capability of 

cell capture while obviating the necessity of further dilution. 

In our application, dilution volumes of pico-femto liter range 

are achieved. 

AFM of an array of laser induced microchannels and microwells on a 

PMMA/PS bilayer film at different laser powers and pulse times. Laser 

spot size is 3μm.

Further improvements of the technique have involved tuning 

the surface energy of the substratum for the tissue section 

from which cells are captured. Glass slides suffer from poor 

transfer efficiency due to protein adhesion. Dewetting a thin 

layer of poly(methyl methacrylate) on polystyrene in a 

temperature gradient yields a surface with varying surface 

energy, microstructure and surface roughness. The ideal 

surface for tissue transfer from the substrate may then be 

mapped in a combinatoric fashion. 

Contributors 

and

Collaborators 

Amit Sehgal, Alamgir Karim, (Polymers Division, NIST) 

Giovanna Cantoni, Robert F. Bonner (NIH) 

near-IR Ga-As

laser beam

λ ∼ 800 nm

cell of interest

Dye incorporated

ELVAX® film on 

backing

Secondary laser beam to 

produce Microwells

Captured cell near-IR Ga-As

laser beam

λ ∼ 800 nm

cell of interest

Dye incorporated

ELVAX® film on 

backing

Secondary laser beam to 

produce Microwells

Captured cell
27
Dental and Medical Materials

28

Dental and Medical Materials 

The Dental and Medical Materials Program provides basic 

materials science, engineering, test methods, and standards to 

sectors of the health care industry for the development of 

new or improved materials and delivery systems. This 

program focuses on (1) evaluation of synthetic materials 

(biomaterials) used to replace or restore function to a body 

tissue and (2) development of improved dental restorative 

materials with greater durability, wear resistance and clinical 

acceptability. 

There is an overall risk of fractures of the hip, spine, and 

distal forearm that will afflict 40 % of women and 13 % of 

men 50 years of age and older. Regenerating form and 

function in bone defects in an elderly, osteoporotic 

population of Americans will be a daunting challenge. To 

meet this challenge, scientists from the Polymers Division are 

developing metrology methods to characterize the 

biocompatibility of bone grafts for bone regeneration. 

Quantitative methods being developed include bioassays for 

the adhesion, viability, proliferation, and alkaline 

phosphatase activity of bone cells, as well as confocal 

microscopy and optical coherence tomography for measuring 

the growth of bone cells into bone grafts. A combinatorial 

approach is being used to rapidly identify compositions and 

surface features of bone grafts that provide desirable 

properties such as biocompatibility and mechanical 

durability. In addition, scientists from the Polymers Division 

are developing reference biomaterials and ancillary reference 

data that will be used by researchers and manufacturers to 

improve performance of human implantable devices, such as 

hip and knee prostheses. 

Polymer based dental composites are fast becoming the 

primary restorative material for the replacement of tooth 

structure that is lost through caries or trauma. Although 

significant strides have been made in improving many of the 

properties of these multi-phase materials, they are still 

considered deficient with regard to their durability, toughness 

and adhesion to contiguous tooth structure. Because of the 

multi-phase nature of composites (polymer matrix plus filler 

plus interface) problems also exist with regard to internal 

adhesion of these three phases. Research efforts focus on 

improving our understanding of the synergistic interaction of 

these phases of the composite as well as elucidating the 

mechanisms of adhesion to dentin and enamel. It is expected 

that these studies will provide a valuable knowledge base for 

the development of dramatically improved composites and 

adhesives. A complimentary study is in progress to develop 

and understand the bioactivity of various types of calcium 

phosphate-filled composites that exhibit remineralization 

potential. 

Contact Information: Francis Wang 
Dental and Medical Materials

29

A Moldable, Resorbable, 

Macroporous, Composite Bone 

Graft Containing Growth 

Factor

Francis W. Wang, Carl G. Simon 

The tissue engineering industry is rapidly expanding and is in 

need of improved measurement technology to aid in the 

development of new biomaterials. We are developing this 

technology through the design and testing of a novel composite 

bone graft. Techniques for assessing cell morphology, 

adhesion and proliferation on opaque specimens such as ours 

are being assessed and the best assays will be proposed as new 

standards to appropriate agencies (ANSI, ASTM, FDA, ISO). 

Thus, this project can yield a new synthetic bone graft as well 

as new standards for use by the tissue engineering industry 

Over 100,000 operations requiring bone grafts are performed 

each year in the United States to repair osseous defects 

resulting from trauma or disease. Autografts are widely used 

by surgeons, but commonly have severe complications such 

as graft rejection, shortage of material and infection and pain 

at the donor site. Thus, the development of synthetic 

materials for use as bone grafts is a primary objective of the 

tissue engineering community. We are using this opportunity 

to develop metrology to serve this burgeoning industry and to 

develop a novel composite bone graft. 

An ideal bone graft should be biocompatible so that it does 

not cause tissue damage, moldable so that it can be sculpted 

to fit the contours of a defect, macroporous (>200 μm dia.) to 

allow for tissue ingrowth, biodegradable so that it does not 

have to be removed and osteoconductive/osteoinductive to 

allow/promote graft replacement with new bone. Our graft 

fits each of these criteria. 

Our graft consists of a calcium phosphate powder and small 

spheres made from a biodegradable polymer that are mixed 

with water to form a paste. The paste can be molded and 

then sets like cement within 30 minutes to form a solid 

matrix of microcrystalline hydroxyapatite that contains the 

polymer spheres. In vivo, the spheres will degrade to leave 

behind macropores for colonization by bone tissue. We are 

assessing the biocompatibility of the composite graft and are 

making the graft osteoinductive by adding bone growth 

factors. 

By facing challenges that are common to the entire tissue 

engineering industry in the context of this real problem, we 

can evaluate and improve the existing biocompatibility 

metrology. Specifically, we have implemented new 

techniques for assessing cell morphology, adhesion and 

proliferation during culture on opaque substrates such as our 

bone graft. We are characterizing new fluorescent indicators 

of cell viability (see Figure) and are improving upon cell 

preparation techniques for environmental scanning electron 

microscopy which allows high resolution imaging of 

hydrated samples. In addition, we are evaluating a new 

colorimetric assay for quantifying cell number that is easier 

to use and faster than standard assays. 

After characterizing our composite bone graft with these new 

techniques, we will move to make the best techniques into 

standardized assays with the appropriate agencies (ANSI, 

ASTM, FDA, ISO). Thus, this project may yield a new 

synthetic bone graft material as well as new standards for use 

by the tissue engineering industry. 

Contributors 

and

Collaborators 

Francis W. Wang, Carl G. Simon, Jr., Chetan Khatri, Scott A. Wight, 

Judy Hsii (Polymers Division, NIST) 

Shozo Takagi (American Dental Association Health Foundation) 

Cells growing on a bone graft specimen which has 

been fluorescently double-stained for live (green, top) 

and dead cells (red, bottom). Both panels are the 

same field of view seen through different filters. 
Dental and Medical Materials Dental and Medical Materials

30

Bioactive Polymeric 

Composites for Mineralized 

Tissue Regeneration 

Joseph M. Antonucci 

Crystalline hydroxyapatite (HAP) is considered to be the final 

stable product in the precipitation of calcium and phosphate 

ions from neutral or basic solutions and it is also the structural 

prototype of the major mineral component of bones and teeth. 

Recently, there has been increasing interest by biomaterials 

community in utilizing polymers of various types as matrices 

and as reinforcements (especially in fiber forms) for calcium 

phosphate-based composites. Customers for this technology 

include dental and biomedical manufacturers and 

practitioners.

Over the broad range of solution conditions when 

precipitation occurs spontaneously, amorphous calcium 

phosphate (ACP) precedes the formation of HAP. ACP has 

been shown to have high solubility in aqueous media and to 

undergo rapid conversion to HAP, especially at low pHs. 

Both of these properties suggest its use as a bioactive filler in 

polymeric materials for the preservation or repair of enamel, 

dentin, cartilage and bone. 

Utilizing conventional dental matrix resins (e.g. 2,2-bis[p-

(2’-hydroxy-3’-methacryloxypropoxy)phenyl] propane (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and 2-

hydroxyethyl methacrylate (HEMA)) and ACP or modified 

versions of ACP as a filler phase, we have prepared 

photopolymerizable bioactive composites that had adequate 

physicochemical and mechanical properties and we have 

demonstrated remineralization potential by sustained release 

of calcium and phosphate ions into simulated saliva media. 

Preliminary studies have shown that certain variations in 

methacrylate resin chemical structure and composition may 

affect the rate and extent of the ion release from ACP-filled 

composites, the internal conversion of ACP into HAP, the 

conversion of methacrylate groups and the mechanical 

properties of the composites. 

Ongoing research is exploring the effects of the chemical 

structure and compositional variations of the resins on the 

release of mineral ions (Ca2+ and phosphate) and the degree 

of vinyl conversion. Conversion is being monitored by near 

infrared spectroscopy. The resins evaluated thus far include 

urethane dimethacrylate (UDMA), and a carboxylic acidcontaining monomer, pyromellitic glycerol dimethacrylate 

(PMGDMA). Acidic monomers, such as PMGDMA would 

be expected to enhance the adhesive properties of the ACP 

composites to tooth structures. The effect of adding a 

potential coupling agent such as zirconyl methacrylate 

(ZrMA) and 3-methacryloxypropyltrimethoxysilane 

(MPTMS) was also investigated. 

In contrast to conventional glass composites, ACP 

composites are relatively weak in mechanical strength. In an 

effort to improve their reinforcing capabilities, we have 

modified ACP during its synthesis with glass-forming agents 

such as tetraethoxysilane (TEOS) and zirconyl chloride. This 

has resulted in modest improvement of mechanical 

properties, such as biaxial flexure strength. Further 

improvements may be feasible by the use of coupling agents 

with these modified ACP fillers. Another strategy for 

enhancing mechanical properties is to employ hybrid filler 

phases consisting of ACP filler admixed with silanized glass 

fillers and /or polymer fibers, such as oriented polyethylene 

fibers. 

Such polymeric calcium phosphate materials are designed to 

be bioactive, biocompatible and highly conformable to 

mineralized tissue. Injectable, photopolymerizable ACP 

composites are feasible for facile clinical use. All ACP 

composites are expected to have significant remineralization 

potential and should find use in remineralizing white spots 

and caries lesions in tooth structure, especially 

interproximally and gingivally. If successful, ACP 

composites would have significant advantages over other 

remineralizing therapies. Currently, a strong need exists for 

protective liners, bases, prophylactic sealants and adhesive 

restoratives that are easily manipulated and that can provide 

efficacious long-term protection against demineralization and 

even have remineralization capabilities. In addition, bioactive 

ACP composites may find wider applications as therapeutic 

materials with the ability to provide osteoconductive 

environments conducive to promoting bone healing, such as 

is needed in dental (endodontic, periodontal etc.) and other 

biomedical applications. 

In related studies other types of calcium phosphate/polymer 

based materials involving vitreous calcium metaphosphate or 

self-setting calcium phosphate cements are under 

investigation. Appropriate methodologies for characterizing 

and evaluating these materials will be utilized. 

Contributors 

and

Collaborators 

J.M. Antonucci, E.D.Eanes, B.O. Fowler (Polymers Division, NIST) 

D. Skrtic, G. E. Schumacher and S. Takagi (American Dental Association 

Health Foundation) 
Dental and Medical Materials

31

Structure-Property

Relationships in Dental 

Polymers

Joseph M. Antonucci 

Polymer based dental materials are increasingly being used in 

dentistry and allied biomedical fields. As part of a joint 

research effort supported by the National Institute of Dental 

and Craniofacial Research and also involving collaboration 

with the American Dental Association Health Foundation 

Paffenbarger Research Center, NIST is providing the dental 

industry and the dental profession with a comprehensive 

knowledge base regarding polymeric dental materials that will 

help elucidate the in-vitro and in-vivo performance of 

materials. 

This project is directed toward enhancing our basic 

understanding of how monomer structure and variations in 

comonomer compositions influence the photopolymerization 

process and the polymeric network structure, both critical 

factors that determine the potential properties that can be 

achieved with dental polymers and their derived materials, 

e.g., composite restoratives. Dental polymers are often 

referred to simply as highly cross-linked networks with little 

or no characterization done beyond a measurement of overall 

vinyl conversion. Although the results of physical and 

mechanical property testing also have been widely reported 

for dental polymers, these data would be more useful with 

knowledge of how monomer structure and resin composition 

variations affect the development of cross-linked polymers. 

Generally this information is difficult to interpret and use as a 

guide for the development of improved materials. 

In addition, the project is intended to define the currently 

unknown co-reactivity of structurally different co-monomers 

that are typically used in dental polymers. For lack of this 

type of information, the reactivity and cross-linking potential 

of dental resins are generally assumed to be equal. The use 

of selected model monomers is designed to demonstrate the 

influence of specific structural features on polymer properties 

and should have significant impact on the development of 

improved materials. An examination of non-methacrylate 

co-monomers, such as vinyl esters, offers a means to modify 

network formation and also appears to allow for higher 

conversion and improved mechanical properties. 

It is known that widely used dental monomers such as the 

hydroxylated dimethacrylate Bis-GMA and the urethane 

dimethacylate UDMA form strong hydrogen bonds that are 

of different types. The effect of hydrogen bonding on 

monomer viscosity is well known but its influence on the 

polymerization process and its potential to influence network 

structure has been overlooked. These aspects are being 

examined along with studies of some model hydrogen 

bonding monomers that may directly provide polymers with 

improved properties. An interesting example of the profound 

effects of hydrogen bonding involved the comparison of 2-

hydroxyethyl methacrylate (HEMA) with its isomer, ethyl αhydroxymethylacrylate (EHMA). The stronger 

intramolecular hydrogen bonding of EHMA vs. HEMA has a 

significant effect on both monomer and polymer properties. 

Also, subtle changes in monomer structure, for example the 

substitution of ether linkages into a predominantly 

hydrocarbon dimethacrylate, can produce dramatic 

differences in polymerization rate and polymer properties. 

The systematic introduction of heteroatoms into 

dimethacrylate monomers is currently being examined to 

explain why these differences exist and how they can be 

employed to obtain polymers with improved properties. The 

use of multi-modal distributions of co-monomers with varied 

chain lengths may offer a simple means to achieve an 

increased level of vinyl conversion, network structure 

variations in the polymer and corresponding improvements in 

the physical, chemical and mechanical properties of dental 

polymers and derived materials. 

A major part of this program is directed at designing 

strategies of maximizing vinyl conversion while minimizing 

polymerization shrinkage. Currently we are investigating 

certain urethane derivatives of Bis-GMA for their efficacy in 

reducing residual vinyl unsaturation and monomer content, 

polymerization shrinkage and the water uptake of their 

polymers. In addition the use of alternative initiator systems 

are under investigation in an effort to enhance 

photopolymerization efficiency and alter polymer network 

formation in its initial stages. While those investigations 

may directly provide improved monomers for dental 

applications, the major thrust of this project is expected to be 

the insights it will provide to aid in the fundamental 

understanding of structure-property relationship that should 

translate into polymeric dental materials with improved 

clinical performance. The utility of the results of these 

studies should extend well beyond the dental materials venue 

to include a significant number of other applications that rely 

on the rapid formation of cross-linked polymeric networks 

with optimal properties from photopolymerizable monomer 

systems. 

Contributors 

and

Collaborators 

Joseph M. Antonucci, Chetan A. Khatri (Polymers Division, NIST) 

Jeffery W. Stansbury (University of Colorado, Boulder) 
Materials for Microelectronics

32

Materials for Microelectronics 

Today’s U.S. microelectronics and supporting infrastructure 

industries are in fierce international competition to design 

and produce new smaller, lighter, faster, more functional, and 

more reliable electronics products more quickly and economically than ever before. 

Recognizing this trend, in 1994 the NIST Materials Science 

and Engineering Laboratory (MSEL) began working very 

closely with the U.S. semiconductor, component and packaging, and assembly industries. These early efforts led to the 

development of an interdivisional MSEL program committed 

to addressing industry’s most pressing materials measurement and standards issues central to the development and 

utilization of advanced materials and material processes 

within new product technologies, as outlined within leading 

industry roadmaps1

. The vision that accompanies this program – to be the key resource within the Federal Government 

for materials metrology development for commercial microelectronics manufacturing – may be realized through the following objectives: 

• develop and deliver standard measurements and 

data; 

• develop and apply in situ measurements on materials and material assemblies having micrometer- and 

submicrometer-scale dimensions; 

• quantify and document the divergence of material 

properties from their bulk values as dimensions are 

reduced and interfaces contribute strongly to properties;

• develop fundamental understanding of materials 

needed in future microelectronics. 

With these objectives in mind, the program presently consists of 

twenty separate projects that examine and inform industry on key 

materials-related issues, such as: electrical, thermal, microstructural, and mechanical characteristics of polymer, ceramic, and 

metal thin films; solders, solderability and solder joint design2

;

interfaces, adhesion and structural behavior; electrodeposition, 

electromigration and stress voiding; and the characterization of 

next generation interlevel and gate dielectrics. These projects are 

conducted in concert with partners from industrial consortia, individual companies, academia, and other government agencies. The 

program is strongly coupled with other microelectronics programs 

within government and industry, including the National Semiconductor Metrology Program (NSMP)3 at NIST. The NSMP is a 

national resource responsible for the development and dissemination of new semiconductor measurement technology. 

More information about this program, and other NIST activities in 

Materials for Microelectronics, can be found at: 

http://www.msel.nist.gov/research.html

---------------------------- 1

 International Technology Roadmap for Semiconductors, 

1999, and National Technology Roadmap for Semiconductors, 1994 and 1997, Semiconductor Industry Association, 

San Jose, CA; National Technology Roadmap for Electronic 

Interconnections, IPC, Lincolnwood, IL, 1995, 1997; National Electronics Manufacturing Technology Roadmap, National Electronics Manufacturing Initiative, Inc., Herndon, 

VA, 1996, 1998, 2000. 

2

http://www.ctcms.nist.gov/programs/solder 

3

http://www.eeel.nist.gov/810.01/index.html 

Contact Information: Wen-li Wu 
Materials for Microelectronics

33

Photolithography

Eric K. Lin, Wen-li Wu 

Photolithography remains the prevalent technology to 

fabricate the smaller feature sizes needed in next generation 

integrated circuits. The development of advanced lithographic 

materials and processes requires new metrology and 

fundamental scientific understanding at these reduced 

dimensions. We apply high-resolution measurement methods 

such as neutron reflectivity, x-ray reflectivity, and small angle 

neutron scattering both to understand fundamental materials 

and transport issues and to characterize the resolution of 

processes using thin film polymer photoresists. 

Photolithography is the driving technology used by the 

microelectronics industry to fabricate integrated circuits. In 

this process, a designed pattern is transferred to the silicon 

substrate by altering the solubility of areas of a photoresist 

thin film exposed to radiation through a mask. To fabricated 

smaller features, next generation photolithography will utilize 

wavelengths requiring photoresist films less than 100 nm 

thick. Many new material and transport problems arise when 

fabricating feature sizes on this length scale. To advance this 

key nanofabrication technology and to evaluate the potential 

of a given process, we are working closely with our 

collaborators at IBM to apply high-resolution metrology to 

better understand processes under localized conditions, to 

guide the development of materials, and to provide high 

quality data. Our efforts are focused in three general areas, 

the physical properties of sub-100 nm polymer films, the 

transport of polymer chains and small molecule components 

over short distances, and the structural characterization of 

lithographically prepared structures. 

 In the first area, we have performed x-ray reflectivity 

measurements to determine the thermal expansion behavior 

of a model thin film polymer photoresist material, 

poly(hydroxystyrene) (PHS). We found that when the film 

thickness is less than 20 nm, the polymer film exhibits an 

8

6

4

2

0

thermal strain (%)

20 40 60 80 100 120 140 160 180

temperature (°C)

 39 Å

 95 Å

 186 Å

 1109 Å

2.5k PHS films

native oxide substrate

Thermal expansion of poly(hydroxystyrene) films with 

varying thicknesses. The curves are offset for clarity. An 

unusual negative coefficient of thermal expansion is 

observed in films less than 20 nm thick.

unusual negative thermal expansion behavior. Additionally, 

as the film becomes thinner, the magnitude of the thermal 

expansion above the glass transition temperature is 

suppressed. This behavior has important implications in the 

stability and processing of thin polymer photoresist films. 

We are now exploring the origins of this thermal expansion 

behavior as a function of polymer relative molecular mass 

and polymer-substrate interaction energy. 

Accompanying these fundamental studies, we have also 

developed the use of small angle neutron scattering (SANS) 

as a new metrology tool for the structural characterization of 

feature size and resolution.

SEM (left) image and SANS data (right) from the same 

lithographically prepared line pattern. The lines are 

nominally 150 nm wide and 620 nm in height.

Unlike current microscopy-based techniques, SANS has the 

advantages of measuring the structure directly on a silicon 

wafer (silicon is transparent to neutrons), becoming less 

technically demanding as feature sizes decrease, and making 

measurements non-destructively. We have demonstrated 

nanometer precision in the average width of a line and a 

methodology to extract the average roughness or resolution 

of line structures shown in the above figure. 

By combining our ability to measure precisely and quickly 

the feature size and resolution of the final structure using 

SANS and fundamental data from high-resolution 

measurements, we plan to develop an integrated program to 

correlate fundamental material and transport issues with the 

ultimate resolution of fabricated structures. 

Contributors 

and

Collaborators 

Eric K. Lin, Christopher L. Soles, Wen-li Wu (Polymers Division, NIST) 

Qinghuang Lin, Marie Angelopolous (IBM) 
Materials for Microelectronics

34

Permittivity of Polymer 

Films in The Microwave 

Range

Jan Obrzut 

To advance miniaturization and functional performance of 

high speed electronics the industry needs high-k polymer 

dielectric materials for integrated passive devices (IPD). 

Development of the IPD technology critically depends on our 

ability to measure and control the permittivity of the dielectric 

materials at microwave frequencies. This project develops 

techniques for accurate measurement of permittivity at 

microwave frequencies and the fundamental framework for 

identifying the key structural and molecular attributes that 

control the dielectric properties of polymer composite films. 

We are investigating electromagnetic properties of polymer 

composite films for dielectric applications in 

microelectronics. These materials are the primary candidates 

evaluated by the microelectronics industry for constructing 

integrated passive devices such as RLC cells and de-coupling 

power planes integrated within chip substrates and printed 

circuit sub-assemblies. Current technologies utilizing 

surface-mounted discrete components cannot provide 

adequate solution at frequencies above 1 GHz, the frequency 

range critical for wireless technologies. In partnership with 

the National Center for Manufacturing Science and industry, 

a collaborative research consortium was organized to address 

this inherent problem. Our current primary goal is to develop 

a broadband measurement methodology based on a coaxial 

configuration for measuring the permittivity of film 

substrates. 

The microstrip-resonator technique, that we developed and 

transferred to the industrial partners, allows for permittivity 

measurements of dielectric films at certain discrete resonant 

frequencies that do not necessarily overlap with the dielectric 

relaxation process. In order to address the structural/dielectric 

attributes in adequate detail broadband dielectric 

measurements are needed. However, the existing test 

procedures for thin films are based on lumped element 

approximations that fail to produce meaningful results at 

frequencies above 100 MHz, especially in the case of highdielectric constant films. We have recently laid down a 

theoretical foundation for accurate broadband permittivity 

measurements of dielectric films at microwave frequencies 

using a coaxial configuration, and demonstrated that it is 

possible to extend the measurements to frequencies well 

above 1 GHz. This has been accomplished by finding an 

appropriate theoretical model for the wave propagation in the 

specimen section, which we treated as a distributed network 

consisting of a transmission line with a capacitance 

terminating a coaxial air-waveguide. Enabling the dielectric 

measurement of films at frequencies of 1 GHz to 10 GHz is 

very important to the industry since it covers the future 

wireless communication bands. The results obtained using 

the new scheme accurately described the complex 

permittivity of polymer films throughout the entire frequency 

range from 100MHz and 10GHz. 

The other objective of this project is to explore the 

relationship between dielectric properties and structure in 

polymeric composites. We evaluated the microwave 

dielectric properties of several polymer-ferroelectric ceramic 

composites newly developed by the industry for integrated 

decoupling capacitors: BC2000 and EmCap from 

PolyClad, CPly from 3M and HiK Polyimide from 

DuPont. These materials measured in a functional thin film 

configuration showed exceptionally good impedance 

characteristics that were attributed to an intrinsic relaxation 

process in polymer composites. 

Study is underway to determine the effect of polarizability of 

the polymer matrix on the apparent dielectric permittivity of 

the composites. Our model system includes a series of 

polymer matrices filled with barium titanate ferroelectric 

powder. Since industry is primarily using cross-linked 

polymer resins, the polymers used in our study are all crosslinkable via photo initiation. We developed a semiempirical model for predicting the composite dielectric 

properties where the parallel coupling between the organic 

and ceramic phases is moderated by an internally induced 

electric field. Our model is applicable over a volume fraction 

above the percolation point and predicts a considerable 

increase in permittivity of the composite when the dielectric 

constant of the polymer matrix increases. Three polymer 

systems with the dielectric constants 3, 4, and 10 were used 

to illustrate the effect of the polymer host. At the ceramic 

loading level of 40 vol. % the high frequency dielectric 

constant of the composite exceeded a value of 40. Our 

broad-band study of the dielectric relaxation provides clear 

evidence that binary mixtures of organic polymer resins 

loaded with ferroelectric powders exhibit an intrinsic high 

frequency relaxation behavior not observed before. Such 

characteristics make polymer composites very attractive for 

broad-band embedded decoupling capacitance applications 

that can secure the signal integrity and minimize the 

electromagnetic interference noise in high-speed circuits 

operating at microwave frequencies. 

Models and measurement techniques developed in this study 

have been identified by a large segment of industrial 

producers as being crucial in new product designs and in 

reducing the development time of new products. 

Contributors 

and

Collaborators 

J. Obrzut, C. K. Chiang, R. Nozaki, R. Popielarz (Polymers Division, NIST), 

J. Dougherty (Penn State Univ.), T. Hubbing (Univ. of Missouri), J. Parker (Allied Signal), 

Y. Lee (DuPont), J. Peiffer (3M), B. Vernell (Polyclad), T. DeRego (HADCO), J. Lauffer (IBM), 

D. Murry (Litton), J. Davignon (Merix), T. Tran (Raytheon), W. Li (Motorola), J. Mayers (DelphiDelco), E. Cullens (TI), R. Charbonneau (Storage Tech.) R. Foly (DOD), L. Patch (NCMS) 
Materials for Microelectronics 

35

Characterization of 

Porous Low-k Dielectric 

Constant Thin Films 

Eric K. Lin, Barry J. Bauer 

NIST is working to provide the semiconductor industry with 

unique on-wafer measurements of the physical and structural 

properties of porous thin films important to their use as low-k 

dielectric materials. We have developed a novel methodology 

utilizing several complementary experimental techniques to 

measure the average pore size, porosity, pore connectivity, film 

thickness, matrix material density, coefficient of thermal 

expansion, moisture uptake, and film composition of several 

classes of candidate porous thin film materials. 

As integrated circuit feature sizes continue to shrink, new 

low-k interlayer dielectric materials are needed to address 

problems with power consumption, signal propagation 

delays, and crosstalk between interconnects. One avenue to 

low-k dielectric materials is the introduction of nanometer 

scale pores into a solid film to lower its effective dielectric 

constant. However, the characterization of the pore structure 

of thin nanoporous low-k dielectric films is not 

straightforward. The small sample volume of 1 μm films and 

the desire to characterize the film structure on silicon wafers 

narrows the number of available measurement methods. We 

have developed a novel combination of small angle neutron 

scattering (SANS), high-resolution x-ray reflectivity 

(HRXR), and ion scattering techniques to determine 

important structural and physical property information about 

thin porous films less than 1 μm thick. These measurements 

are performed directly on films supported on silicon 

substrates so that processing effects can be investigated. 

HRXR is used to accurately measure the film thickness, the 

average film electron density, and the coefficient of thermal 

expansion. SANS is used to determine the pore structure 

providing information such as the average pore size, pore 

connectivity, and moisture absorption. Ion scattering 

techniques are used to determine the elemental composition 

of the films. 

During the past year, we have focused our efforts into three 

areas: characterizing current industrially relevant materials 

through International SEMATECH, gaining fundamental 

understanding of different classes of material preparation, 

and conducting an international round robin comparison of 

different on-wafer measurement techniques. International 

SEMATECH, a consortium of microelectronics companies, 

provided more than 25 separate samples for characterization 

by NIST, including spin-on glass materials, films from 

chemical vapor deposition, and organic thin films. The 

structural information provided by NIST is placed into a 

master database that includes data from a variety of sources, 

detailing both the structural and material properties needed to 

evaluate candidate materials. Member companies make 

extensive use of the data to guide the development of low-k 

dielectric materials for integration into future devices. 

0.1

1

1 0

10 0

I (cm -1 )

8 9

0.0 1

2 3 4 5 6 7 8 9

0.1

2

q (Å -1)

 A

 B

 C

Representative small angle neutron scattering data from 

three different types of porous low-k dielectric thin films. 

We have also collaborated with several groups including 

researchers at Dow Corning, Lucent, and Sandia National 

Labs to provide measurements to better understand 

fundamental issues in general classes of sample processing 

methods. Finally, we have established an international 

collaboration including private, government, university, and 

corporate research groups from NIST, IMEC (Europe), ISP 

(Novosibirsk), the University of Michigan, the Kyushu 

Institute of Technology, CCIC, Ltd. in Japan, and Dow 

Corning to critically compare data from several different 

on-wafer measurement methods for the structure of porous 

thin films. The techniques, including the NIST methodology, 

ellipsometric porosimetry, and positron annihilation lifetime 

spectroscopy, are used to determine average pore size, film 

porosity, pore connectivity, pore wall density, and the pore 

size distribution. It is expected that the results from this 

collaboration will provide a needed overview and practical 

guidelines for researchers to rigorously characterize the 

structure of porous low-k dielectrics. 

Contributors 

and

Collaborators 

E.K. Lin, B.J. Bauer, H. Lee, H. Wang, W. Wu (Polymers Division, NIST) 

Jeff Wetzel, Changming Jin, Jeffrey Lee (International SEMATECH) 

Mikhail Baklanov (IMEC), David Gidley (University of Michigan) 

Wei Chen, Eric Moyer (Dow Corning), Shu Yang (Lucent) 

Hongyou Fan, C. J. Brinker (Sandia National Laboratory) 
Materials for Microelectronics

36

Measurement of In-Plane 

CTE and Modulus of 

Polymer Thin Films 

Martin Y.M. Chiang, Chwan K. Chiang 

Polymer thin films are used in many electronic packaging 

applications. The satisfactory operation and fabrication of 

many devices depends critically on the integrity of films to 

withstand hostile end use and processing environments. 

Characterization of thin films is important to predict the 

lifetime and to ensure a successful fabrication process. Our 

objective is to develop a simple and reliable measurement 

technique for determining the in-plane coefficient of thermal 

expansion (CTE) and elastic modulus of supported thin films, 

two parameters dictating the level of residual stress in devices. 

There have been many methods developed to measure the 

properties of thin films widely used in electronic packaging 

applications. Two important properties for thin films in their 

packaging applications are CTE and elastic modulus 

because they govern the residual stresses. Excessive 

residual stress can often lead to the failure of the electronic 

devices. A number of methods are available to probe the 

CTE and elastic modulus of supported thin films. The basic 

concept among the methods is that the CTE and modulus 

can be calculated through equations connecting the response 

of a film/substrate system perturbed mechanically, 

thermally, acoustically, or optically. 

We have applied a non-contact bending plate technique to 

measure the in-plane CTE and modulus of polymer thin 

films deposited on rigid substrates. Figure 1 shows 

schematically the measurement set-up of a bimaterial 

circular plate consist of a thin film and a substrate; the 

bending results from a mismatch in CTE between the thin 

film and the substrate. Under a constraint free condition, 

the plate will deform to a spherical shape when its 

temperature is different from a reference temperature at 

which the plate is stress-free. Figure 2 shows a typical 

image of a deformed plate and numerical data of measured 

deflection from a test specimen. 

t

d

R

Wafer

Film

SCAN

Laser

light

Detector

 Fig. 1 

To calculate both CTE and modulus, it is necessary to 

measure the deformation of two different samples (using the 

same film material but different substrate materials) at the 

temperatures. This provides a set of two coupled algebraic 

equations with two unknowns (CTE and modulus of the 

film). In the previous approach, the residual stress of the film 

was first calculated from the bending curvature; the CTE and 

modulus were then calculated by differentiating the stress as 

a function of temperature. There are two major deficiencies 

in this approach; both the CTE and the elastic modulus are 

assumed to be constant over the temperature range studied, 

the differentiation process often lead to additional uncertainty 

in the final results. In our work the film properties are 

directly calculated based on the bending curvature at any 

given temperature provided the reference (stress free) 

temperature has been determined beforehand. Our approach 

is more robust than the previous one; it does not require 

differentiation and can provide the in-plane CTE and elastic 

modulus of a supported thin film at each measurement 

temperature. For polymeric materials this capacity is rather 

desirable because both elastic modulus and CTE of polymers 

often exhibit strong temperature dependence. 

Fig. 2 

Contributors 

and

Collaborators 

M. Y. M. Chiang, C. K. Chiang, and W. L. Wu (Polymers Division, NIST) 

 D. Feiler and W. Xia (Conexant Systems, Inc.), Dow Chemicals

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60 70 80

DISTANCE (mm)

DEFLECTION (μm)

BARE SILICON

FILM on SILICON
Materials for Microelectronics

37

Electronic Paper 

Chad R. Snyder, Erik K. Hobbie 

In our progression towards a “paperless” society, new display 

methods are critical – one of the more promising display 

classes is based upon electrophoresis; prediction of the 

properties of these systems is non-trivial. NIST is attempting to 

develop the metrology and fundamental knowledge for 

characterizing micro- and nano- particle suspensions in terms 

of their electrophoretic bistability and switching speed. As a 

part of this project, the fundamental effect of particle size on 

the bulk dielectric properties of nanofilled materials is being 

examined. 

To understand the electrophoretic response of E-paper, the 

dielectric properties of the individual particles need to be 

determined. This is a general problem that is particularly 

pressing in the area of modeling nanoparticle dispersions 

where the particles are in between “molecular” and 

“macroscopic” states. Therefore, while the electrophoretic 

behavior is the main thrust of this project, a large fraction of 

the effort has been directed towards determining the length 

scale over which continuum models of the dielectric constant 

are applicable. 

Electrophoretic Phenomena. To examine the dynamic 

response and bistability of electrophoretic suspensions, a 

sample cell was designed and constructed that allows video 

microscopy measurements of micro-scale colloidal 

suspensions in the presence of static and dynamic electric 

fields. We have focused on suspensions of 3 μm polystyrene 

(Latex) particles in buoyancy matched solutions of 50/50, by 

volume, water/heavy water. This cell has been used to 

measure the dynamic response of suspensions in contact with 

ion exchange resin to sudden application and removal of 

static electric fields of 6/5 V/cm. (Migration of the particles 

to one of the electrodes is “pixel on”; switching the fields off 

or reversing the bias is “pixel off”.) Preliminary 

measurements suggest that space charge plays a significant 

and complicated role in the dynamic response and bistability 

of such monodisperse suspensions, and future experimental 

and theoretical work will attempt to address this issue. 

As part of the future work to explore the feasibility of adding 

a small amount of a second, smaller colloidal component to 

promote entropic clustering and enhance bistability, 

measurements of internal dynamics and gel/crystalline 

elasticity have been performed for entropic monolayers 

confined to a glass surface, and measurements of the kinetics 

of phase separation and crystallization in buoyancy-matched 

polymer-colloid and colloid-colloid mixtures have recently 

been completed. 

Dielectric Properties of Nanofilled Systems. To determine on 

what size scale continuum mixture models can be reasonably 

applied, i.e., where the “solvent effect” is negligible, a model 

“spherical” nanofilled system was examined – 

buckminsterfullerene (C60) in solvents of various polarities. 

The static dielectric constant ε of C60 particles was 

determined in cis-decalin, toluene, and 1,2-dichlorobenzene 

(ODCB) using continuum models for spherical and spherical 

shell inclusions. Spherical-shaped models were deemed to be 

reasonable after modeling was performed on the geometry of 

the truncated icosahedron (C60 geometric shape). For 

comparison, the relationship for ε of a dilute mixture of solid 

truncated icosahedrons differs from that of a perfect sphere 

by only 1 % of ε (i.e., a factor of 3.0409 vs. 3 for a sphere). 

The value for ε for isolated C60 in cis-decalin and toluene 

agreed well with molecular beam measurements using a 

spherical shell model, but the ε estimate in the highly polar 

solvent ODCB deviated from these other measurements. 

Preliminary measurements have indicated large deviations of 

molecular beam and solution measurements of ε of C60 in the 

case of the highly polar solvent, ODCB. Polar solutions are 

subject to a number of complications and it is not yet clear 

where fundamental modifications of the continuum model are 

necessary. 

A great deal of further experimentation will be necessary to 

determine whether or not continuum models can successfully 

predict bulk material properties of nanoparticle filled 

materials based upon the appropriate parameters for the 

matrix and the inclusions. However, we feel that this work 

does suggest that careful choice of a matrix will allow for 

determination of the dielectric properties of nanometer-scale 

objects. It should also be possible to extend this approach to 

many other properties of interest (shear modulus, refractive 

index, magnetic permeability, etc.) so this simple method 

promises to have wide applicability. 

Contributors 

and

Collaborators 

Chad Snyder, Erik Hobbie, Jack Douglas (Polymers Division, NIST) 

Marc Mansfield, Stevens Institute of Technology 

James Martin, Sandia National Laboratory 
Materials for Microelectronics

38

Hygrothermal Expansion 

of Polymer Thin Films 

Chad R. Snyder, Wen-li Wu 

Polymer thin films are widely used in electronics packaging 

applications, however the properties of these thin films can be 

significantly different from those of the material in its bulk 

form. We are providing the electronics industry with robust 

measurement tools and data for characterizing the dimensional 

stability of polymers. NIST has designed, developed and 

demonstrated the capabilities of a capacitance-based 

metrology with outstanding sensitivity for measuring the outof-plane expansion of these thin films. 

We are currently engaged in several activities to aid in the 

adoption of our capacitance-based metrology by industrial 

users. The first such activity involves extending the 

measurement capabilities of the technique to a wider variety 

of samples. To this end, a capacitance cell that can measure 

the thermal expansion of insulators, semiconductors, and 

conductors, has been designed, constructed, and tested. The 

accuracy of the new capacitance cell design for thermal 

expansion measurements on conducting and semiconducting 

samples has been demonstrated by measurements on a 0.6 

mm thick p-doped <100> oriented single crystal silicon. As 

can be seen in the plot, our data are in excellent agreement 

with the recommended expansion data. 

A second activity that is currently being pursued to accelerate 

the adoption of our technique involves working with 

standards-setting bodies to explore the desirability of 

introducing the technique as a standard method for measuring 

thermal and hygrothermal expansion. After extensive 

discussions with the chairperson of The Institute for 

Interconnecting and Packaging Electronic Circuits’ (IPC) 

HDIS Test Methods Group, the format for our test method 

has been decided upon and is in a draft form. 

-50

0

50

100

150

200

250

300

350

400

450

280 300 320 340 360 380 400 420

Temperature (K)

(d - d 25)/d 25 x 106

Thermal expansion of single crystal <100> oriented 

silicon relative to its value at 25 °C (d25). The line 

corresponds to the recommended expansion data from 

the literature. (The error bars are the best estimate of two 

standards deviations in the experimental uncertainty.)

One final activity involves working directly with industrial 

users that have identified a specific use for the capacitance 

cell metrology. In this activity, we provide them with detailed 

designs for construction of the capacitance cell and work 

with them to modify the designs to better serve their 

purposes. Currently, we are working with two such users: 

Los Alamos National Laboratory (LANL) and Xerox 

Corporation, both of whom have received the detailed 

instructions for construction of the capacitance cell electrodes 

and holder. LANL has expressed great interest in adopting 

the capacitance cell metrology for measuring the swelling of 

thin polymer films in the presence of supercritical fluids and 

has been in contact with the NIST Optical Shop regarding 

construction of their own capacitance cell. Xerox 

Corporation is interested in using the metrology for 

measuring the coefficient of hygrothermal expansion of thin 

polymer films. 

The capacitance cell methodology is capable of handling 

films with thicknesses above 2 μm. However, needs exist for 

measuring thermal expansion of films one μm thick or less. 

One noticeable example is the industrial need of the 

coefficient of thermal expansion (CTE) of interlevel 

dielectrics used in on-chip interconnects. To meet this need, 

equipment and measurement protocols based on high 

resolution x-ray reflectivity have been developed; the CTE of 

films with thickness ranging from 5 nm to 1.3 μm has been 

routinely collected and the results have been disseminated to 

International SEMATECH and many material suppliers. 

Contributors 

and

Collaborators 

Chad Snyder, Wen-li Wu (Polymers Division, NIST) 

Angela Strongy, Xerox Corporation 

Jim Wheat, Los Alamos National Laboratory 
Materials for Microelectronics

39

Assembly Of IC Chips 

Using Wafer-Level 

Underfill

William E. Wallace, Daniel Josell 

For area-array flip chip applications, the microelectronics 

industry has a well-established need for an underfill system 

that obviates the time-consuming flow required by current 

viscous polymeric underfill materials. The most promising 

route to accomplishing this is the application of an integrated 

underfill/solder bump system at the wafer stage. We have 

provided materials data and computer simulation that show 

behavior to be expected during assembly of flip chips that have 

an underfill/solder bump system applied at the wafer level.

This project addresses the critical problem of wetting 

behavior of solder in solder joint interconnections under the 

constraints found in the wafer-level underfill systems. The 

pre-existing underfill geometry provides constraints on the 

flow of the solder, influencing the self-alignment of the die 

and final solder joint geometry. These factors have profound 

effects on joint reliability. Thus, behavior of the solder 

during reflow is a critical aspect of the underfill system, 

which is itself supposed to enhance reliability. 

The three specific goals of this project are: 1) create 

modeling software for evaluating capillary induced 

realignment forces; 2) carry out validation experiments for 

realignment forces provided by solder joint to misaligned 

pads; 3) develop a model incorporating capillary realignment 

forces as well as viscous forces retarding realignment 

associated with polymer underfill material. 

The accomplishments to date are: 

Software based on the freeware Surface Evolver code 

has been written that allows modeling of two relevant joint 

geometries. This software was placed on the CTCMS web 

site: http://www.ctcms.nist.gov/~djl/solder/new.html

Measurements of solder joint dimensions, specifically 

stand-off height and lateral offset (i.e., misalignment), as 

functions of the applied force (normal and shear), solder size 

(0.029, 0.0086, 0.0063 and 0.0019) mm3

, and pad diameter 

(0.65 and 0.35) mm were conducted. 

A manuscript entitled “Misalignment of flip-chip 

solder joints: prediction and experimental determination of 

lateral and normal force-displacement curves” (D. Josell, 

W.E. Wallace, J.A. Warren, D. Wheeler, and A.C. Powell) 

was submitted to The Journal of Electronics Packaging.

FIGURE: Cross-sectioned 0.35 mm solder joints. From top 

to bottom the lateral shear force is: 34 μN , 68 μN, 1.0 mN 

and 1.2 mN. Normal forces are approximately 1.95 mN. Pad 

dimensions are not exactly 0.35 mm because cross-sections 

do not exactly bisect pads. This introduces no error in the 

measured lateral offset because any cross-section parallel to 

the displacement direction for two circular pads will yield the 

same value. 

Contributors 

and

Collaborators 

William Wallace (Polymers Division, NIST) 

Daniel Josell (Metallurgy Division, NIST) 
Multiphase Polymeric Materials

40

Multiphase Polymeric Materials 

The multiphase polymeric materials program develops 

realistic measurement and characterization platforms for 

multiphase polymeric materials that use a combination of 

experimental measurements and theoretical and computer 

(T/M) modeling tools to provide realistic and highly 

optimized output. These measurement and characterization 

tools and platforms are intended to help industries in preproduction evaluation, materials characterization and 

performance prediction, as well as provide data for process 

design. 

In order to achieve the performance requirements in modulus, 

stiffness, toughness, temperature, chemical and environmental 

stability, and even provide the desired appearance and touch, 

most polymeric materials in use are either phase separated 

blends with two or more components, and/or filled with 

particles or short/long fibers. The challenge in using 

multiphase polymeric materials extends from the processing 

design, through structure and properties prediction and 

characterization to service life prediction. This program is 

designed to use theoretical and computational modeling tools 

in conjunction with characterization measurements to form 

realistic and workable tool sets. 

Specifically, characterization techniques will be developed 

and used to generate relevant data bases or constitutive 

relations to be used as input for theoretical and computer 

modeling tools to provide more realistic T/M and bridge the 

gap in current T/M tools. Current theoretical and 

computational tools are capable of modeling fine length scales 

such as nano-scale molecular dynamics simulations, microscale self consistent field or density functional methods, and 

meso-scale time dependent Ginsburg-Landau or CahnHilliard-Cook techniques. On the other hand, macroscopic 

part sized finite-element-flow calculations and Object 

Oriented Finite element analysis (OOF) for properties 

calculations and virtual testing are much coarser grained tools. 

A seamless connection between these two sets of computer 

tools is not available to provide realistic materials properties 

for design, prediction, and characterization. 

This program is currently working on three materials 

characterization projects to provide: 1. Phase 

separation/crystallization results together with interfacial 

characterization and rheological data to form constitutive 

relations as input for finite-element-flow modeling, and 

characterization of phase structure. 2. Structure, dynamics, 

and modulus characterization in high surface area particle 

filled polymers and blends for performance characterization 

and validation of multiscale computer modeling. 3. Fiber tow 

characterization and failure results as input to finite-element 

based mechanics and performance evaluation. All three 

projects are linked to future poly-OOF for property prediction 

and virtual testing. 

This program works with industrial companies through 

collaboration, CRADAs, and consortium arrangements. This 

includes resin suppliers, system suppliers, parts producers, and 

auto-industry and offshore oil platform companies for method 

and technique dissemination. 

Schematic showing the influence of percolation on the 

dynamic behavior of bound polymer chains. Top – 

Unpercolated filler aggregates with bound polymer (red) 

compared to unbound polymer (blue). Bottom – 

Percolated filler aggregates with bound polymer (red) 

compared to unbound polymer (blue). 

Contact Information: Charles C. Han 
Multiphase Polymeric Materials

41

Constitutive Relationship 

of Polymer Blends for 

Process Modeling Needs 

Erik K. Hobbie, Charles C. Han 

The ultimate morphology obtained in polymer blending is a 

complicated function of blend phase behavior, processing 

conditions, and mold geometry. By combining a universal 

picture of blend morphology and phase behavior under shear 

with the flow properties of a given mold geometry, we hope to 

produce a software package that will predict blend properties, 

and hence performance, as a function of position within the 

final product. 

The first stage of this project is to garner a detailed and 

quantitative understanding of the equilibrium phase behavior 

of a number of different polyolefin blends. In addition to 

phase separation, these blends exhibit subsequent 

crystallization upon cooling, and the work to date has 

focused on the influence that phase separation has on the 

kinetics of spherulitic growth. Once this aspect of the 

morphology is well understood, the focus will shift to the 

non-equilibrium phase behavior under shear flow, from 

which a constitutive relationship encompassing temperature, 

pressure, shear rate, and blend composition will be 

formulated. From this relationship, we seek to predict 

droplet shape, composition, and phase after quenching a 

blend into a mold of arbitrary geometry. This would enable 

industrial users to predict material performance a priori

under different conditions, hence optimizing and enhancing 

product quality. 

The materials on which we have focused are polyolefins with 

statistical copolymers of ethylene/hexene (PEH) and 

ethylene/butene (PEB). Here only PEH is primarily 

crystallizable. Because of the almost identical refractive 

index, optical measurements are difficult. The phase 

boundary (temperature/composition) has been determined in 

three different ways; a combinatorial technique that uses 

photo intensity in the presence of a temperature gradient 

following a quench to room temperature, a measurement of 

the transmitted light intensity, and small angle light 

scattering. From this we get the complete phase diagram, 

which shows typical upper critical solution temperature, 

UCST, behavior (Tc = 146 o

C, φPEH = 0.44) intersected by a 

line of crystallization. 

To study how the liquid-liquid phase separation limits the 

crystallization, we used time-resolved small-angle light 

scattering, time-resolved wide- and small-angle X-ray 

scattering, optical microscopy, and atomic force microscopy. 

For optical measurements, phase-separated samples are 

quenched to room temperature, where subsequent 

crystallization introduces sufficient optical contrast to 

discern liquid-liquid domains. In future studies, one of the 

polymers will be labeled with a co-monomer that will 

enhance the difference in refractive index between the two 

components, thus allowing us to directly visualize the phaseseparated domains under simple shear flow. 

 A novel feature suggested by the data is that the presence of 

domain interfaces arising from liquid-liquid segregation acts 

as an inhibitor to crystallization at late times, so the size of 

the spherulites becomes kinetically pinned. The situation is 

thus complicated, since crystallization kinetics is influenced 

by both the composition of the internal phase and the shape 

and size of the phase-separated droplet. The kinetics of 

spherulitic growth can be adjusted with respect to the phase 

ordering kinetics by varying the isothermal temperature. 

Contributors 

and

Collaborators 

H. Wang, A. Nakatani, G. Schmidt, K. Shimizu (Polymers Division, NIST) 

M. Langhorst, Wu (Dow Chemical) 

D. Nguyen (PPG) 

A. Halasa (Goodyear) 

R. Weiss (University of Connecticut) 

0.0 0.2 0.4 0.6 0.8 1.0

390

395

400

405

410

415

420

425

φc

 ~ 0.44

Tc ~ 419 K

Tm

Phase Diagram of PEH/PEB, χ=-5.5x10-4+0.5/T T (K)

φPEH

 Experiment

 Binodal

 Spinodal
Multiphase Polymeric Materials

42

PB/PI Blend Morphology

0.1

1

10

100

0.001 0.01 0.1 1 10

Shear Rate (1/s)

R (micron)

L/W (aspect raio)

Characterization and 

Modeling of Interfaces 

and Interphases of 

Polymeric Systems 

Frederick R. Phelan Jr., Charles Han 

The injection molding of polymer blends produces a complex 

microstructure in which drops of one phase are dispersed in a 

matrix phase. The detailed morphology depends on the fluid 

mechanical deformation history, component rheological 

properties, and blend thermodynamics. The goal of this project 

is to gain a fundamental understanding of the interplay 

between process parameters and blend microstructure, and 

develop a computational software tool for predicting the 

microstructure evolution of polyolefin blends in injection 

molding operations for industrial users. 

We are currently engaged in a project to predict the 

microstructure that forms during the injection molding of 

polymer blends. Polymer blend mixtures are generally 

injection molded while phase separated. In such systems, 

droplets of a dispersed phase are suspended in a matrix 

phase. Blend mixtures usually enter an injection molding 

cavity with more or less uniform drop size from an extruder. 

However, upon entering the cavity, the drops are highly 

sheared and break-up into finer and finer sizes near mold 

walls, and relax (and possibly even coalesce) towards 

equilibrium sizes in regions of low shear. This leads to a nonuniform “skin-core” microstructure in the final part, which 

highly affects properties. 

We are in process of putting together a simulation that 

predicts drop size distribution and morphology in injection 

molded polymer blends. The first activity is a measurement 

program in which we measure drop size and aspect ratio as a 

function of shear rate and composition in blend mixtures. 

Example data for a polyisoprene-polybutadiene blend is 

shown in the figure to the right. In addition, the shear 

viscosity as a function of composition is measured. 

As a first order model, these data are employed in custom 

subroutines for viscosity and drop size to the commercial 

fluid dynamics package FIDAP. From the computed shear 

rates, we can map the final drop size distribution in the mold. 

An example is shown in the lower figure. As expected, the 

model predicts a very small drop size at the wall, which 

gradually increases towards the center. 

This simulation represents a first order method for predicting 

morphology in polymer blend mixtures. It is only first order 

because it predicts that the drop size changes instantaneously 

with shear rate, whereas in actual systems, at a given shear 

rate it takes a finite time for break-up to occur. We are in the 

process of studying dynamic effects through flow simulation 

and development of appropriate theory. However, for thin 

cavities with no recirculations, the first order model is 

expected to yield adequate results except near the entrance 

region. 

Contributors 

and

Collaborators 

F.R. Phelan, Jr., E.K. Hobbie, H. Wang, C.C. Han, S. Glotzer (Polymers 

Division, NIST) 

Tinh Nguyen (Building Materials Division, NIST) 

Polymer Interphase Consortium (NIST, Dow Chemical, PPG, Visteon) 
Multiphase Polymeric Materials

43

Synergistic Interactions 

Of Polymers With High 

Surface Area Nanofillers 

Alamgir Karim, Charles Han 

The use of fillers to modify polymers has long been an 

important aspect of the polymer industry. With an increased 

emphasis toward tailoring material properties instead of 

simply providing inexpensive extending agents, a 

comprehensive fundamental understanding of filled polymers is 

preferable to current empirical approaches. The objective of 

this project is to provide a fundamental understanding of the 

mechanism of polymer reinforcement with particulate 

materials and correlate these measurements with mechanical 

behavior and desirable material properties. 

The research topics are based on a survey of industrial needs 

conducted at a workshop on Interactions of Polymers with 

Fillers and Nanocomposites sponsored by the NIST Polymers 

Division. The topics include: 1) the dynamics of polymer 

bound to the surface of carbon black fillers determined by 

inelastic neutron scattering, NMR and microscopy methods, 

2) molecular dynamics simulations of polymers near a filler 

surface, the structure and properties of nanoclay-polymer 

suspensions under shear by flow birefringence, rheological 

methods and in-situ shear small angle neutron scattering 

(SANS) experiments, 3) the influence of particles on the 

phase separation behavior of polymer blends by light 

scattering and calculational methods, and 4) the suppression 

of dewetting behavior in nanofilled polymer thin films. 

The dynamics experiments indicate that the dynamics of the 

bound polymer layer are different for carbon black 

concentrations below and above the percolation threshold of 

the carbon black. This indicates that the state in which the 

bound polymer is prepared is as important as the amount of 

bound polymer. Coupled with the dynamics calculations, an 

improved understanding of the mechanism of reinforcement 

is possible. 

Model filler particle interacting with polymer chains.

The dynamics calculations show that the Tg shifts and surface 

dynamics observed experimentally can be explained by the 

nature of the polymer-filler interaction. A flattening of the 

polymers near the filler surface was also observed, which is 

largely insensitive to the polymer-filler interactions. The 

results provide guidance for the design of custom filled and 

nanofilled materials and support for an explanation of the 

origin of Tg shifts in polymer thin films in terms of surface 

interactions. 

The results on the flow behavior of clay-polymer solutions 

show an unexpected orientation of the clay platelets during 

flow and provide evidence for a dynamic network between 

the polymer chains and clay platelets that explains some of 

the viscoelastic behavior of these solutions. The work 

provides a reference point for similar studies on flow 

behavior of bulk nanocomposites and thin film studies. 

Schematic of orientation of clay platelets and polymer chains 

during shear in the SANS shear cell.

Simulations of phase separation at high filler content show 

strong interference effects in the concentration wave around 

the filler particle that have a profound effect on the phase 

separation morphology. Various surface treatments shift the 

phase boundary of a blend reflecting the interaction strength 

between the filler and blend components. 

The work resulted in a CRADA with Dow Corning Corp. that 

will characterize polymer kinetics and dynamics near the surface 

of silica fillers. SANS studies will be conducted on end-linked, 

labeled chains incorporated into a filled network as a function of 

deformation and type of filler. Another CRADA with Michelin 

Americas Research and Development Corp. will measure the 

dynamics of styrene-butadiene rubber (SBR) as a function of the 

monomer ratio by various neutron scattering techniques. 

Selectively labeled copolymers will allow observation of the 

individual comonomers. 

Contributors 

and

Collaborators 

A. Karim, C. Han, G. Schmidt, A. Nakatani, J. Douglas, D.-W. Liu, V. Ferreiro, 

D. VanderHart, S. Glotzer, F. Starr (Polymers Division, NIST) 

 R. Ivkov, P. Papanek, P. Butler, R. Dimeo (NIST Center for Neutron Research) 

Dow Corning Corporation, Sid Richardson Carbon Co., Southern Clay Products 
Multiphase Polymeric Materials

44

Mechanics of Fiber and 

Nano-Filled Composites 

Gale Holmes, Charles Han 

To facilitate the use of composites in automotive and 

infrastructure applications, computational models are needed 

that predict composite failure behavior and establish failure 

probabilities for composite structures. In this project, a 

measurement platform is being developed that determines the 

energy dissipation mechanisms that govern the initiation and 

propagation of damage in composites using data from fully 

constrained model composites. These data will link 

micromechanics failure parameters to tow-based failure 

behavior using the chain-of-bundles modeling approach. 

This new project builds on expertise gained from NIST 

research on factors that influence adhesion at the fiber-matrix 

interface of fibrous composites. In this project, 3-D multifiber model composites are being investigated to quantify the 

impact of fiber-fiber interactions on the deformation and 

failure behavior of composites. Fiber-fiber interactions are 

known to be a key micromechanics parameter that must be 

accounted for if composite failure behavior is to be 

understood and modeled using computational tools. Existing 

data from 2-D (partially constrained) multi-fiber arrays have 

shown that the adhesion and failure behavior of a fiber is 

influenced by the presence of fibers that are within 5 fiber 

diameters. Current micromechanics models cannot account 

for this behavior. In addition, nucleation and propagation of 

crack clusters in composites are poorly understood. As an 

example, Monte Carlo simulations using the chain-of-bundles 

modeling approach have been successful in qualitatively 

capturing changes in the failure behavior of unidirectional 

composites. In the model, altering the value of the fiber 

Weibull shape parameter captured the change from brittle to 

brush-like failure behavior. Experimentally, the change in 

failure behavior was achieved by changes in the matrix 

properties, fiber-matrix adhesion, and fracture toughness of 

the fiber-matrix interface strength and not by changing the 

fiber. 

A critical shortcoming of 2-D array research is that the 

prediction of stress-concentration factors on the fiber 

adjacent to a fiber break could not accurately be predicted by 

the local load-sharing rules used in the chain of bundles 

model. This discrepancy was attributed in part to the lack of 

total constraint around the broken fibers. Therefore, the key 

parameters that are needed to predict fiber tow failure from 

micromechanics data must be obtained from 3-D fiber arrays. 

To achieve the third dimension in a hexagonal array the 

spacing between layers at 1 fiber-diameter must be 

approximately 13 μm. Since the fiber diameter variation 

between fibers is (15 ± 5) μm, variations in the interlayer 

spacing of approximately (3 to 4) μm are acceptable. We 

propose to achieve the third dimension by building sets of 

steel steps graduated by the appropriate spacing to achieve 

the desired inter-fiber spacing (see Figure 1). 

Figure 1 

Each array of fibers will span across the matched steps to 

achieve equal spacing between fibers within the layer. 

Milling the sets of steps to achieve the desired interlayer 

spacing will push the limit of machining technology. To 

minimize variability within a layer, the contact pressure on 

each fiber set will be controlled by the weight of a cross bar. 

This metrology will provide NIST with the unique capability 

of generating model composite systems with controlled and 

systematically variable fiber architectures in 3-D. This 

technology will provide the basis for linking micromechanics 

failure parameters with computational models that can 

predict the macroscopic failure of composites and aid in the 

establishment of failure probabilities for composite structures 

in the automotive and offshore industries. 

Contributors 

and

Collaborators 

W. McDonough, J. He, E. Feresenbet, J. Dunkers, D. Hunston (Polymers 

Division, NIST) 

L. Phoenix (Cornell University), J. Nairn (University of Utah) 
Multiphase Polymeric Materials

45

Structure-Property

Characterization and 

Modeling

Donald Hunston, Charles Han 

To remain competitive internationally, industries as diverse as 

transportation, infrastructure, aerospace, and off-shore oil 

require the ability to engineer lightweight composites and 

structural polymers to achieve advanced properties. The key 

technology is the ability to predict behavior from the material’s 

microstructure since that structure controls performance. This 

project focuses on the role of microstructure in properties 

important to industry and formulates advanced 

micromechanics models that will enable optimization of 

properties for a material through control of its microstruture. 

This project includes a variety of engineered polymers and 

polymeric systems, but the current focus is hybrid composites 

that are polymers reinforced with two or more different types 

of fibers. By combining the advantageous features of 

different fibers, industry can achieve significantly better tradeoffs between various properties and between cost and 

performance. Unfortunately, the design methodology for 

hybrids is inadequate. Different test methods often give 

different values for the same property and current theories for 

predicting behavior are unreliable. The problem is that the 

failure modes and the interpretation of test results depend on 

details of the sample microstructure in ways that we do not 

understand. Moreover, characterizing this microstructure is a 

challenge since the available tools have not been developed 

nor adapted to these types of systems. 

This program uses model hybrid materials to develop 

techniques for characterizing sample microstructure. Samples 

with known microstructure are then tested in multi-axial 

loading to determine properties. The University of Houston is 

collaborating in this effort by conducting tests on large 

specimens while NIST is characterizing small-scale samples. 

Based on these results, new models are being developed which 

utilize the detailed microstructure and micromechanics to 

predict performance. 

The initial focus in the program is filament wound hybrids 

(glass and carbon fibers) that are of interest to the off-shore 

oil industry. The studies have emphasized transverse shear 

behavior since that is critical for buckling failure. Not only 

failure behavior but also modulus has been difficult to 

determine and predict. For example, data from tests on tubes 

and plates do not agree. With plate samples the test involves 

the Iosipescu specimen (see figure). During the past year, 

this specimen has been analyzed and several important 

problems have been identified. The area of the specimen that 

is important for the test is a small region between the two 

notches where the shear stress field exists. To obtain valid 

results, this region must be large enough to encompass the 

details of the microstructure that can be in the mm size scale 

for hybrid composites. On the other hand, the strain gage 

used in the test must be small enough to fit within this region. 

Detailed experiments and finite element analyses 

were conducted to determine these size limits for hybrids. 

This result is very important for industry since the alternative 

to the Iosipescu test is experiments on torsion of tubes that 

requires expensive equipment and samples. 

Finite element mesh for analysis of Iosipescu specimen 

A second development in this program was the extension of 

current ASTM burn-off tests for constituent content to include 

hybrid composites. This work has demonstrated that the NIST 

modified test method provides a simple and inexpensive way 

for industry to determine the content of glass fibers, carbon 

fibers, resin, and voids in a sample. Such information is 

critical for analyzes such as that described above or for the 

prediction of properties. Although some work remains to 

verify the accuracy with which the contents can be 

determined, it is expected that a finalized version of the 

modification can be submitted next year to ASTM for 

consideration. 

A third accomplishment in the program involves prediction 

of dynamic behavior for tube structures made with hybrid 

composites and that is described elsewhere in this report. 

The work to date has focused on stiffness properties of the 

hybrids and has had good success in resolving many of the 

questions that existed. Next year, the focus will turn to 

failure behavior. 

Contributors 

and

Collaborators 

D. Hunston, W. McDonough, M. Chiang, F. Phelan, G. Holmes, S. Glotzer, J. 

He, N. Parekh (Polymers Division, NIST) 

S.S. Wang, G. Williams (University of Houston) 

D. Johnson (Lincoln Composites) 
Multiphase Polymeric Materials

46

Modification of the Phase

Stability of Polymer Blends

by Filler Additives

Alamgir Karim, Alan Nakatani 

Polymeric materials are often modified with additives that alter 

processability, modulus, impact strength, conductivity, and 

other properties. These mutiphase mixtures are often unstable 

over long periods of time, leading to property degradation. 

Controlling the phase boundary of these dispersions has 

practical importance because the temperature difference from 

the phase boundary (quench depth) is a primary factor 

governing the stability of these mixtures. The influence of filler 

on the phase stability of a model polymer blend is investigated. 

Building on earlier work on phase separation in bulk 

polymer materials, the effect of filler additives on phase 

separation was studied by adding fumed silica particles to a 

model polymer blend. The surface properties of the filler 

particles were modified to determine how this factor 

influenced the phase boundary shifts. We find that filler 

additives can shift the phase boundary and that the effect is 

dependent on the polymer-surface interaction and the filler 

concentration. 

Cloud point measurements were performed on model blends 

of polystyrene (PS) and polybutadiene (PB) with fumed 

silica particle additives that were subjected to different 

surface treatments. Cloud points were measured by placing 

mechanically mixed filled blends on a microscope slide 

positioned on a temperature-controlled hot-stage and 

monitoring scattered light intensity (Fig. 1). 

Figure 1. Schematic of experimental apparatus 

Fig. 2 shows the cloud point curve for filled and unfilled 

PS/PB blends. The filled blend data correspond to mass 

fractions of (1 and 5) % fumed silica particles without 

surface treatment. The filler particles lead to a decrease of 

the blend miscibility; there is little change in the critical 

composition of the filled blend. The shift of the critical 

temperature increases with the filler content. Cloud-point 

measurements were insensitive to the period of mechanical 

mixing between the blend and the filler in the compounder. 

Figure 2. Temperature (°C) versus relative PS Mass 

Fraction; error bars represent standard uncertainty.

The critical point for phase separation can be shifted up or 

down through the addition of additives that have a varying 

relative affinity for the blend components; these effects have 

been investigated to a limited extent theoretically. Grafting 

polystyrene chains on the surface of the filler particles led to a 

slight decrease of the cloud point while treatment by the silane 

coupling agent (BMDMCS) led to a substantial downward 

shift of the phase boundary (Fig. 3), in qualitative accord with 

theory. 

 Figure 3. Cloud point Temperature (°C) versus 

relative filler mass fraction 

Contributors 

and

Collaborators 

A. Karim, A. Nakatani, J. Douglas, D.–W. Liu (Polymers Division, NIST) 

J. de Groot (Dow-Corning)

70

80

90

100

110

120

0123456

Untreated

PS

BMDMC

S

T

c

 (oC)

Mass Fract. Filler 

70

80

90

100

110

120

0 0.2 0.4 0.6 0.8 1

Pure

1% Fumed silica

5% Fumed silica

PS Mass Fract.
Multiphase Polymeric Materials

47

Nanofiller-Induced

Suppression of Dewetting in

Thin Polymer Films

Alamgir Karim, Jack F. Douglas 

Thin films are increasingly used in applications involving 

dielectric coatings, resist layers for lithography, electronic 

packaging, optical coatings, lubricating surfaces, etc. 

Producing stable and defect-free films is particularly 

problematic in very thin films (thickness, h<10 nm) where 

thermally induced fluctuations at the air surface induce the 

film to rupture. We demonstrate that it is possible to suppress 

the dewetting of thin polymer films through the introduction of 

nanoparticle additives.

The effect of a model nano-particle fillers 

[buckminsterfullerene, C60, or/and “buckyballs” (BB), silica 

beads] on the dewetting of polymer films on inorganic 

substrates was investigated. The BB and silica filler particles 

strongly suppressed the dewetting of the thin polymer films, 

in contrast to larger filler particles that promoted dewetting 

by heterogeneous nucleation. Recently, we have shown that 

the suppressed dewetting also occurs for silica nanofillers 

and for lipid films containing membrane proteins, so the 

effect has some generality. 

Optical images (shown in the figure below) of 50 nm thick a) 

polystyrene (PS) and b) polybutadiene (PB) films spun cast 

onto Si wafers show ordinary dewetting at annealing 

temperatures above their glass transition. Corresponding 

films of c) PS and d) PB at the same thickness and under the 

same annealing conditions with 1% BB (φ, mass fraction of 

BB) show a strong suppression of dewetting. Atomic force 

microscopy images of thinner films (20 nm) showed pinhole 

defects that are not apparent in optical images for BB 

concentrations below 0.5%. 

b) d)

a) c)

Neutron reflectivity (NR) measurements of a 100 nm PS film 

with 5% BB indicate a diffuse layer of BB at the Si substrate 

formed during spin casting. There is no evidence from NR or 

contact angle measurements that the BB segregate to the air 

surface. 

The presence of BB at the substrate apparently pins the 

polymer dewetting contact line, implying a dependence on 

BB concentration. This is confirmed experimentally. Films 

without the BB filler form holes that grow and coalesce to 

reach complete dewetting. Films with small amounts (0.01% 

and 0.1%) of BB show hole formation without hole growth. 

As the BB concentration is increased further, the hole size 

diminishes below the limits of optical and AFM observation. 

The key feature of the suppressed dewetting appears to be the 

immobilization of the filler and the nanoscale size of the 

filler. The BB layer at the substrate surface is diffuse and 

pins the contact line of dewetting holes at an early stage. The 

extent of dewetting is controlled by the amount of BB in the 

range 0 < φfiller < 0.01. For φfiller > 0.01 there is complete 

suppression of holes in L < 50 nm films.

Contributors 

and

Collaborators 

A. Karim, J. F. Douglas, A. I. Nakatani, D.–W. Liu (Polymers Division, NIST) 

K. A. Barnes (Dow-Corning)

-6

-5

-4

-3

-2

-1

0

Log R

q ( nm-1 ) 0 0.5 1.0 1.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80 100 120

φ

Depth Z (nm)

fullerene 0

50

100

150

200

250

300

350

0 10 20 30 40 50 60

Anneal time (min)

Hole size (μm)

Pure PS

0.01% BB

0.1% BB

1% BB

Polymer layer

Diffuse BB layer ~ 5nm
Polymer Characterization

48

Polymer Characterization 

The Polymer Characterization Program provides 

measurement methods, data and standard reference materials 

(SRMs) needed by U.S. industry, research laboratories, and 

other federal agencies to characterize rheological and 

mechanical properties of polymers, their processibility and 

performance, and to improve process control. In response to 

the critical needs of industry for in-situ measurement 

methodologies, a substantial effort is underway to develop 

optical, dielectric and ultrasonic probes for use in extrusion 

and injection molding. Improved methods for determining 

molecular mass distribution of polymers are developed owing 

to the dramatic effect it has on processibility and properties. 

Mechanical properties and performance are significantly 

affected by the solid-state structure formed during 

processing. Importantly, unlike many other common 

engineering materials, polymers exhibit mechanical 

properties with time dependent viscoelastic behaviors. As a 

result, the program also focuses on techniques that measure 

the solid-state structure and rheological behavior of 

polymeric materials. 

Chromatographic techniques, which require calibration by 

standards of known molecular mass, are the principal 

methods for determining molecular mass distribution. 

Because calibration standards are lacking for most polymers, 

crude approximations must be used to interpret 

chromatographic data. Recent program activities exploit 

advances in mass spectrometry using matrix assisted laser 

desorption ionization (MALDI) to develop the method as a 

primary tool for the determination of the molecular masses of 

synthetic polymers, with particular emphasis on 

commercially important polyolefins. Advances are sought in 

measurements of solid-state structure of polymers, including 

optical coherent tomography (OCT), inelastic neutron 

scattering, and sum frequency generation spectroscopy. 

The extrusion visualization facility combines in-line 

microscopy and light scattering for the study of polymer 

blends, extrusion instabilities and the action of additives. 

Current research focuses on understanding and controlling 

the "sharkskin instability" in polymer extrusion. 

Fluorescence techniques are developed to measure critical 

process parameters, such as polymer temperature and 

orientation that were hitherto inaccessible. These 

measurements are carried out in close collaboration with 

interested industrial partners. 

The polymer industry and standards organizations assist in 

the identification of current needs for standard reference 

materials. Based on these needs, research on characterization 

methods and measurements are conducted leading to the 

certification of standard reference materials. Molecular 

standards are used primarily for calibration of gel permeation 

chromatographs, the principal method employed by industry 

for assessing molecular mass and molecular mass 

distributions. Melt flow standards are used in the calibration 

of instruments used to determine processing conditions for 

thermoplastics. Non-Newtonian rheological standards are 

also developed to exhibit the typical polymeric behaviors of 

shear thinning and normal stresses; these standards are also 

used for calibration of rheological instruments and for 

research into improved measurement methods. Reference 

biomaterials are produced for test method harmonization, 

assessment of new materials and generation of reference data. 

Contact Information: Bruno Fanconi 

1.9 mm 

3.0 mm 

Scaffold 

Pore 

OCT cross-sectional image of a hydrogel tissue scaffold.
Polymer Characterization

49

Optical Coherence 

Tomography for Material 

Characterization

Joy P. Dunkers 

The need for non-destructive, subsurface microstructural 

characterization of materials in the micrometer to millimeter 

size scale is great. A volumetric representation of the internal 

structure of a material is often required to understand how 

various properties of interest are interrelated. NIST has 

brought optical coherence tomography (OCT) to the realm of 

material science. We are using OCT for meso-scale, volumetric 

characterization that cannot be obtained by any other 

technique and are applying it to polymer composites, polymer 

blends, biomaterials, and ceramic coatings. 

Optical coherence tomography (OCT) is a non-invasive, noncontact optical imaging technique that allows the 

visualization of microstructure within scattering materials. 

OCT uses a near-infrared low coherence source and a 

scanning fiber optic interferometer for depth discrimination. 

Reflections generated from material heterogeneity are 

collected as a function of depth. Transverse scanning in the 

remaining two planes by motorized stages generates the 

volumetric image. OCT is a high sensitivity technique that 

can detect back-reflections as low as femtowatts with a 

resolution of (5 to 30) μm. 

This past year we constructed a table-top OCT system with a 

reference mirror capable of scanning a maximum of 7.5 mm. 

The actual depth within the sample is the distance traveled by 

the reference mirror divided by the group refractive index of 

the sample. The system has three motorized stages, each with 

10 cm of travel. The sample rests on two of the three stages 

that scan in perpendicular directions to create a volumetric 

image set. The third stage is used to adjust the focus of the 

beam onto the sample. The resolution of the system is 15 μm

in the thickness direction (z axis) and (5 to 100) μm in the 

transverse directions (x and y axes), depending upon choice 

of objective. The system possesses a sensitivity of >110 dB. 

To evaluate the potential of OCT we compared it to microfocus x-ray computed tomography (x-ray CAT), the only 

other technique that is non-destructive and yields volumetric 

images of resolution similar to OCT. The comparison was 

performed on a selected region of impact damage in a glassreinforced thermoset composite. OCT revealed the 

reinforcement architecture and damage with 10 μm to 20 μm

spatial resolution. Several damage mechanisms were found 

and were identified to be kink banding, fiber/matrix 

debonding, longitudinal cracking, and matrix deformation. 

All of these mechanisms were consistent with damage 

expected from bending a composite with a tough matrix and 

poor fiber-matrix bonding. The limitations of OCT were that 

the fiber architecture was not imaged clearly throughout the 

entire specimen thickness. The images were subject to 

artifacts such as shadowing, contrast degradation as a 

function of thickness, and degradation of spatial resolution. 

X-ray CAT clearly imaged the tow stacking throughout the 

entire sample but was insensitive to the stitching. Owing to 

sensitivity and resolution limitations, the fiber/matrix 

debonding and kink-band damage were seen together as one 

barely visible region. The matrix deformation shown by OCT 

was not visible. OCT provided superior sensitivity and 

resolution in this analysis. 

OCT has been historically used for medical imaging. NIST is 

bridging the gap between materials science and medicine by 

using OCT to non-destructively elucidate the meso-scale 

structure of biomaterials. An important consideration with 

biomaterials is working in aqueous medium to mimic their 

natural state. OCT is able to image biomaterials in-situ.

A tissue scaffold is a substrate upon which cells are grown in 

order to generate a living tissue with a specific function. 

Most tissue scaffolds are porous to allow for cell migration 

and proliferation. Characterization of the scaffold porosity is 

one important aspect in evaluating scaffold viability. An 

OCT cross-sectional image of a hydrogel tissue scaffold in 

water is shown below. The light gray areas are the water 

filled pores and the darker gray areas are the scaffold 

material. Note that the microstructure seen by OCT is 

significantly different than what would be seen in a 

dehydrated sample prepared for scanning electron 

microscopy. OCT can generate volumetric information on 

average pore size, size distribution, and connectivity. 

Contributors 

and

Collaborators 

J. Dunkers, C. Simon, N. Washburn (Polymers Division, NIST) 

J. Chuang (Ceramics Division, NIST) 

M. Everett (Livermore National Laboratory), P. Davis (Optiphase, Inc.), 

J. Kohn (Rutgers University), W. Green (Army Research Laboratory) 

1.9 mm 

3.0 mm 

Scaffold 

Pore 

OCT cross-sectional image of a hydrogel tissue scaffold.
Polymer Characterization

50

Advanced Metrology for 

Surface and Interface 

Chemical Analysis 

William Wallace 

The chemical structure at both the free surface and buried 

interfaces of polymeric materials is often critical to their 

performance as it can control such properties as adhesion and 

wear. Molecular characterization of these interfaces is 

difficult: conventional surface science probes often do not have 

the specificity to broadly characterize complex chemical 

moieties. We have explored three cutting-edge techniques to 

surmount this long-standing challenge: vibrationally-resonant 

sum-frequency generation, cluster-beam secondary ion mass 

spectrometry, and near-edge x-ray absorption fine structure. 

Vibrationally-resonant sum-frequency generation is a 

non-linear optical technique in which an infrared photon and 

a visible photon are mixed to produce a new photon at the 

sum frequency. It has all the advantages of linear vibrational 

spectroscopies, and the additional characteristic that it is 

symmetry forbidden in amorphous and centrosymmetric 

media. Thus it is uniquely interface sensitive. We have made 

the first measurements of the absolute molecular 

orientational distribution of a pendant side group at a 

polymer surface. At the polystyrene/air interface, the 

pendant phenyl groups are oriented away from the film and 

tilted from the surface normal in an angular range near 60°.

The phenyl groups are suggested to point outward either as a 

means to seek the maximum free volume, or possibly as the 

lowest free energy conformation that smoothes out the abrupt 

change in density due to the presence of the free surface. 

Cluster-beam secondary ion mass spectrometry uses 

polyatomic incident ions (e.g., SF5

+

) to improve secondary 

ion yield for increased surface sensitivity and also for 

improved depth resolution for more precise thin film 

profiling. This has resulted in a better than ten fold increase 

in the secondary ion yield of poly (methyl methacrylate) 

samples while the damage depth stays on the same order as 

the sputter region. This gives much improved surface 

sensitivity. Future work will focus on quantifying the 

improvement of depth resolution using multilayer samples. 

Carbon near-edge x-ray absorption fine structure was 

used to detect both surface and bulk segmental relaxation in 

uniaxially-deformed polystyrene samples. We have 

demonstrated that by simultaneously monitoring the partial 

electron yield (kinetic energy > 150 eV) and the 

fluorescence yield (carbon Kα 277 eV) NEXAFS signals, 

with probing depths of approximately 2 nm and 200 nm, 

respectively, one can, in a single experiment, examine 

segmental motion throughout a polymer sample. Using this 

methodology, chain relaxation is found to occur almost 50% 

faster at the surface than in the bulk. This finding is expected 

to profoundly influence the design, processing, and 

application of all polymeric materials. 

Figure: Time evolution of the orientation factor, OF, from an 

elongated (oriented) polystyrene sample reveals that when 

annealed at 60 °C the surface chains relax to an equilibrium 

(unoriented) configuration faster than the bulk chains. OF is 

calculated from (I|| - I⊥)/(I|| + I⊥), where I|| and I⊥ are the 

1s → π1* resonance NEXAFS intensities collected with the 

sample elongation direction parallel (φ = 0°) and 

perpendicular (φ = 90°) to the electric vector of the soft X-ray 

beam, respectively. The blue circles denote OF from the 

partial electron yield NEXAFS signal (surface region) and 

the red circles represent the fluorescence yield NEXAFS 

signal (bulk region), measured simultaneously. The closed 

and open circles depict OF evaluated from data collected on 

elongated specimens and those not subjected to elongation, 

respectively. The solid lines represent exponential decay fits 

to the experimental data on the elongated samples. 

Contributors 

and

Collaborators 

W. Wallace, W. Wu (Polymers Division, NIST), D. Fischer (Ceramics Division, 

NIST), L. Richter, G. Gillen (Surface & Microanalysis Science Division, NIST) 

K. Briggman, J. Stephenson (Optical Technology Division, NIST) 

Luke Haney (U. Ill.-Chicago) 

Jan Genzer (NC State)

0 40 80 120

1 0 -3

1 0 -2

1 0 -1

oriented

surface

bulk

unoriented

O rientation function

A nnealing tim e (m in)
Polymer Characterization

51

Molecular Mass 

Distribution of Polymers by 

Mass Spectrometry

Bruno Fanconi, Charles Guttman 

The molecular mass distribution (MMD) of a polymer has 

profound effects on how it is processed and the resultant 

properties. Recent advances in Matrix Assisted Laser 

Desorption Ionization (MALDI) Time of Flight (TOF) Mass 

Spectroscopy (MS) suggest that it is possible to obtain the 

MMD of undegraded polymer molecules with molecular 

masses up to 300,000 g/mol. MALDI is explored as a method to 

obtain the measurement of the absolute molecular mass of a 

polymer molecule, as well as a tool to obtain the molecular 

architecture of a polymer. 

 Interlaboratory Comparision Using MALDI TOF MS

With the objective of providing the polymer industry with a 

measure of the robustness of the MALDI ToF MS method to 

obtain the MMD of a synthetic polymer, the NIST Polymers 

Division, in cooperation with the American Society of Mass 

Spectrometry (ASMS) Working Group on Synthetic Polymers, 

conducted an interlaboratory comparison of MALDI ToF MS. 

Samples of well-characterized low molecular mass polystyrene 

were sent to any institution requesting it. 

A total of 23 institutions participated in the interlaboratory 

comparison (10 industrial, 9 academic, and 4 government 

laboratories). NIST Polymers Division also characterized the 

polymer by NMR for Mn and by light scattering for Mw.

Fourier transform infrared spectroscopy, FTIR, confirmed the 

presence of the t-butyl end group, as anticipated by the 

synthesis method. Size exclusion chromatography was used to 

insure vial-to-vial homogeneity in the samples distributed to 

participants. Each participating laboratory was asked to 

perform MALDI mass spectrometry using two distinct 

protocols. 

By compiling all the returned data using both protocols into 

one analysis it was found that MALDI ToF MS returned an Mn

of (6610± 100) g/mole and an Mw of (6740 ± 90) g/mole, 

uncertainties are standard uncertainties. These numbers were 

below those of the classical methods, but still within the 

overlapping uncertainty ranges. Detailed results of this study 

have been submitted for publication to Analytical Chemistry. 

The intent is to certify the polymer used in this study as a 

Standard Reference Material SRM 2888. 

Polymer Architecture of Polysilsequioxanes 

Polysilsesquioxanes are used in industry as an alternative to 

siloxanes in applications where strength, thermal stability, or 

chemical resistance are at a premium. Polysilsesquioxanes 

are three-dimensional polymers with a repeat unit of the form 

[RSiO3/2] in which each silicon atom is coordinated with 

three oxygen atoms. 

One important unknown in the processing of silsesquioxanes is 

the “degree-of-condensation” of the prepolymer before it is 

converted into the final monolith. The prepolymers of the 

polysilsesquioxanes were studied by MALDI ToF MS by the 

NIST Polymers Division. In all cases the number of 

intramolecular Si-O-Si bridges per oligomer was found to be a 

linear function of the number of repeat units in the oligomer. It 

is not possible to obtain this result by other measurement 

techniques like NMR or FTIR. 

This work lead to a CRADA with Dow Corning. NIST 

provided the measurement expertise in MALDI ToF MS of 

silsesquioxanes (SSQ) and Dow Corning provided the 

siloxane- SSQ copolymers of commercial interest. Dow 

Corning also performed extensive fractionation in order to 

narrow the broad molecular mass distribution in an effort to 

facilitate the mass spectrometry. The MALDI ToF MS data 

obtained when analyzed by special data analysis techniques 

NIST had developed led to the discovery of quite surprising 

results that the SSQ monomers appear in even numbers in this 

copolymer.

Contributors 

and

Collaborators 

C. Guttman, W. Blair, R. Goldschmidt, W. Wallace, B. Fanconi, J. Antonucci, 

(Polymers Division, NIST) 

S. Wetzel (Department of Chemistry, American University) 

D. Katsoulis, R. Techlenberg (DowCorning ) 
Polymer Characterization

52

Standard Test Method 

Development

Charles Guttman, Bruno Fanconi 

The U.S. polymer industry routinely characterizes its products, 

their processibility and performance with test methods that 

while convenient, require calibration by known standards. 

Principal polymer standards are certified for molecular mass 

and melt flow rate; the former is used to calibrate size 

exclusion chromatographs and the latter to calibrate melt flow 

indexers. Quantification of mass spectrometry as a method for 

determination of molecular mass distribution is undertaken as 

the basis for development of a standard method for analysis of 

synthetic polymers. 

With recent advances in mass spectrometry it is possible to 

measure the molecular mass of some biological and synthetic 

polymers. Among the advances is a variation of time-offlight mass spectrometry, ToF MS, matrix assisted laser 

desorption ionization, MALDI, in which laser ablation is 

used to produce charged polymers in the vapor state. This 

technique has the potential to be an absolute method for 

measuring the molecular mass distribution (MMD) of 

synthetic polymers, a long sought after goal in polymer 

characterization. The mass distribution of a synthetic 

polymer is the most important molecular characteristic that 

impacts its processibility and macroscopic properties. There 

are no other methods of determining this important molecular 

characteristic of synthetic polymers, although separation 

techniques, such as gel permeation chromatography, provide 

relative measures of MMD and other techniques yield 

average values of the MMD. However, chromatographic 

instruments must be calibrated with polymer standards that 

have narrow MMD and are similar chemically to the polymer 

being tested. These polymer standards are certified for 

averages of the molecular mass distribution by classical 

methods (light scattering, membrane osmometry, 

sedimentation equilibrium ultracentrifugation ). Since such 

standards are unavailable for most polymers, crude 

approximations are used which introduce uncertainties in the 

measurement results. 

Reported comparisons of MMD by MALDI ToF MS with 

data obtained by classical methods reveal unsettling 

discrepancies that must be resolved before the method is 

accepted. To address the need for quantification of MALDI 

ToF MS we have initiated, with the collaboration of 

laboratories in Canada, Japan, Germany and Italy, a technical 

working activity under the auspices of VAMAS, the 

Versailles Project on Advanced Materials and Standards. The 

VAMAS activity will investigate the effects of sample 

composition & preparation, instrument settings and data 

analysis on the quantitativeness of MALDI ToF MS 

spectroscopy. 

The initial focus is to develop a standard test method for 

determination of the MMD of polystyrene by this method. 

Polystyrene was selected owing to the availability of 

essentially mono-dispersed commercial samples, the success 

to which MALDI MS data can be obtained and results of the 

recent NIST led interlaboratory comparison of PS using 

MALDI ToF MS that laid the basis for quantification studies. 

The specific objectives are: 

1) Sample composition and preparation method, including 

recommended matrix materials, metal salts, solvents, mixture 

concentrations and sample deposition procedure. The SEM in 

the figure below is from a sample deposited by electrospray. 

2) A set of guidelines for MALDI-ToF-MS to obtain 

instrument settings and mass calibration. 

3) Procedures and guidelines for analyzing mass spectral 

data. 

An ancillary output is polystyrene reference materials 

certified for molecular mass distribution and averages of the 

molecular mass distributions for testing MALDI ToF MS 

instruments and procedures. 

Contributors 

and

Collaborators 

S. Wetzel (Department of Chemistry, American University) 

S. Weidner (Bundesanstalt für Materialforschung und –prüfung, Germany) 

S. Kinugasa (National Institute of Materials and Chemical Research, Japan) 

G. Montaudo (University of Catania, Italy) 

L. Li (University of Alberta, Canada) 
Polymer Characterization

53

Non-Newtonian Standard 

Reference Materials for 

Rheology

Carl Schultheisz 

Characterization of the flow behavior of polymeric fluids is 

critical to efficient processing. Polymeric fluids typically 

demonstrate complex, non-Newtonian fluid flow behavior, 

such as a viscosity that depends on shear rate and normal 

stresses. The viscoelastic behavior of two polymeric fluids (a 

polymer solution and a polymer melt) will be characterized 

in steady and dynamic shear over a temperature range from 

0 °C to 50 °C. These fluids will serve as benchmarks to 

compare the performance of rheometers in situations 

involving complex fluids. 

Polymer melts and solutions typically do not follow the 

simple Newtonian ideal in their flow behavior, demonstrating 

shear-rate dependent viscosities and normal stresses. Such 

fluids see wide application in everyday life (injection 

molding, paints and coatings, food products, etc.), and the 

ability to accurately measure and characterize their behavior 

is very important to optimizing their processing conditions. 

Since there are a number of commonly used methods to 

measure the flow behavior of polymers, the new Standard 

Reference Materials (SRM 2490 and SRM 2491) will 

provide a way for comparing the performance of different 

instruments, as well as providing tools for research into better 

methods of measuring the rheological properties of polymeric 

fluids. The new fluids will be certified for the shear-rate 

dependence of viscosity and first normal stress difference at 

temperatures of 0 °C, 25 °C and 50 °C. The linear 

viscoelastic responses will also be certified along with the 

temperature dependence of the shift factors over the same 

temperature range. 

 The new polymer solution, SRM 2490, consists of 

polyisobutylene (molar mass approximately 106

 g/mol) 

dissolved in 2,6,10,14-tetramethylpentadecane. The 

branched structure of this solvent inhibits crystallization or 

vitrification down to at least -60 °C, while the relatively high 

molar mass of the solvent reduces its rate of evaporation. 

Cannon Instruments mixed and packaged 438 units, 100 mL 

each. Measurements of SRM 2490 in steady and dynamic 

shear have been completed; results from steady shear testing 

are shown in the accompanying figures. Twenty samples 

were tested at each temperature, using cone and plate fixtures 

in a strain-controlled rheometer. 

SRM 2491 will consist of a poly(dimethylsiloxane) melt. 

This fluid will have somewhat less temperature dependence 

than the solution SRM 2490. 

This project will also include a round robin test of the 

Standard Reference Materials among instrument 

manufacturers and users in industry and at universities. The 

round robin will investigate the lab-to-lab variability in these 

measurements; the variability in the first normal stress 

difference is of particular interest. 

Contributors 

and

Collaborators 

S. Leigh (Statistical Engineering Division, NIST) 

G. McKenna (Texas Tech University) 

Cannon Instruments, State College, Pennsylvania 

Shear Rate (s-1)

0.001 0.01 0.1 1 10 100

Viscosity (Pa s)

10

100

1000

Shear Rate (s-1)

0.001 0.01 0.1 1 10 100

First Normal Stress Difference (Pa)

1

10

100

1000

10000

0 °C

25 °C

50 °C

50 °C

25 °C

0 °C

Viscosity and First Normal Stress Difference in

Steady Shear. Symbols are measured quantities;

lines are models that incorporate time-temperature

superposition fit through all the data simultaneously.
Polymer Characterization

54

Support for the 

Biomaterials Integrated 

Products Industries 

John A. Tesk 

NIST workshops have established that the medical devices 

industry has needs for reference materials, test methods, and 

reference data. This project is established to continually assess 

NIST ability to help meet technical needs of BIPI's. In addition 

to workshops, needs are explored through participation on 

numerous standards boards and their committees, on 

committees/boards of professional societies and academic 

institutions, and via liaisons with the National Institutes of 

Health and the Food and Drug Administration. 

A series of NIST workshops, with participation of the 

Biomaterials Integrated Products Industries, BIPI's, 

established needs for measurement methodology, reference 

biomaterials and reference data. NIST responded to the need 

for an accelerated, wear-test method for the screening of new 

materials for orthopaedic joint implants through formation of 

the Orthopedics Research Consortium. At a Reference 

Materials, RM, Workshop in 1998, the need for a RM of 

medical grade ultra high molecular weight polyethylene, 

MG-UHMWPE, bar stock was identified for replacing the 

dwindling supply that had been made available for 

orthopaedic research by the Hospital for Special Surgery. 

NIST issued a replacement RM in October 2000. That 

workshop also identified the need for a RM of MGUHMWPE reference material, wear-debris particulate. On 

July 27, 2000, a workshop was held to explore the potential 

of need for a Standard Biomaterials Properties Reference 

Database (SBPRD). Participation on committees/boards of 

standards organizations, professional and academic 

organizations, and the NIH (member of Steering Committee 

for NIH produced workshop on Implant Retrieval and 

Analysis, Jan 10-12, 2000) helped further toward 

understanding of BIPI needs and for establishing useful 

relationships. Publications were also pursued to provide 

greater visibility of NIST to the BIPI’s community. 

The development of a method to produce MG-UHMWPE 

wear debris particulate is in progress under the direction of 

Dr. Steve Hsu of the NIST Ceramics Division. 

The workshop on Standard Biomaterials Properties 

Reference Data identified the need for several databases and 

for RMs for ophthalmic, orthopaedic, dental, cardiovascular, 

and tissue-engineered materials. 

Active participation in ASTM assists in meeting needs of 

BIPI’s in standards and test methods. A new method for 

determination of degree of cross-linking in irradiated 

UHMWPE is under final evaluation through round robin 

testing. Interest in irradiated MG-UHMWPE stems from the 

positive effect on wear resistance. A better method of 

determining the molecular response to irradiation will assist 

in optimization of the process. 

NIST assisted in the round robin by providing cubes of its 

new reference material MG-UHMWPE for use in the round 

robin. These samples will be irradiated at several doses and 

distributed to laboratories for measurement of degree of 

cross-linking using the draft method. Supporting the interest 

in radiation treatment of MG-UHMWPE, NIST will make the 

cubes available for purchase as a RM for comparison 

purposes. 

Progress on the development of ophthalmic RMs involves 

collaboration among NIST, Louisiana State University, 

Alcon Industries and NIH. The need for specific RMs and 

ancillary reference data have been established through the 

collaboration. 

NIST Materials Science and Engineering Laboratory is 

becoming recognized as an integral part of biomaterials 

standards, test methods, and research community (beyond the 

dental community). NIST participation in development of 

standards and reference materials is sought and is looked to 

for playing a key role in coordination of such efforts. 

.

Contributors 

and

Collaborators 

J. Tesk, F. Eichmiller (Polymers Division, NIST); S. Hsu (Ceramics Division, 

NIST); J. Colbert, J. Thomas (Standard Reference Materials Program, NIST); J. 

Rumble, J.Fuller (Standard Reference Data Program, NIST); 

NIH; FDA; Biomet; Depuy, a J&J Company; Stryker Howmedica Osteonics and 

Zimmer; Polymer Technology Group; Alcon Industries; Genzyme; Poly Hi 

Solidur 
Polymer Characterization

55

Semicrystalline Polymer 

Structure by Small Angle 

Scattering

John Barnes 

Processors and users of products formed from semicrystalline 

polymers need improved descriptors of microstructural 

characteristics in order to control properties of their materials. 

The method of temperature-induced contrast variation as 

pioneered in this project provides a means of separating the 

lamellar stack microstructure from voids and other matrix 

effects, thereby affording improved identification of 

mechanisms that influence properties such as toughness, 

modulus, clarity, and permeability. 

In 1999 we demonstrated [1] that the variation in scattering 

contrast arising from differences in thermal expansion 

between the amorphous and crystalline components of 

semicrystalline thermoplastic materials could be used to sort 

out multiple contributions to the small-angle scattering from 

these materials. We refer to this as temperature-induced 

contrast variation (TICV). In calendar year 2000 the SANS 

part of this work was extended to cover a broader 

temperature range. Complementary WAXD and SAXS 

studies were undertaken on anisotropic semicrystalline 

polyolefin samples in order to characterize the threedimensional character of the scattering from these materials. 

Figure 1 depicts part of the data from this study. The highdensity polyethylene sample was prepared from a shotgun 

shell casing that is often used as a reference for orientation 

texture studies. The poly(4-methyl-1-pentene) sample 

(P4MP)was prepared by subjecting compression molded 

plaques to channel die extrusion at a temperature just below 

their crystallization temperature. In both instances the 

resulting sample symmetry is strongly orthorhombic, as is 

shown in the SAXS patterns in figure 1. 

These patterns were obtained at the Exxon/Mobil beamline 

(X10A) at the National Synchrotron Light Source. Each 

specimen was in the form of a rectangular prism with the 

flow direction oriented along the long axis of the specimen, 

which is the vertical axis in Figure 1. The SAXS patterns are 

sections through the 3-d intensity distribution and were 

collected at fixed angles of 0, 30, 60, 90, ... 360o. The 

WAXD patterns were obtained by integrating the scattered 

intensity over the full 30o rotation step. 

WAXD data were collected only at room temperature, while 

SAXS data were collected over a range of temperatures far 

enough below the melting point to avoid significant 

morphological change. The P4MP SAXS patterns in Figure 1 

were collected at 145  ̊C. The corresponding patterns were 

basically invisible at temperatures below 65  ̊C, in keeping 

with our earlier observations on the very strong TICV effect 

in this polymer. 

The lack of suitable basis functions for the anisotropic form 

factor of the lamellar stack represents a further challenge to 

the interpretation of these data. 

The continuation of this work involves transfering the 

necessary data collection protocols and data reduction 

software into Small Angle Scattering (SAS) beam lines at 

other active SAS centers, so that the method can be applied 

to a broader range of polymer products. 

Figure 1: WAXD and SAXS from two highly oriented 

polyolefin specimens as a function of specimen 

orientation. 

1. J.D. Barnes, R. Kolb, K. Barnes, A.I. Nakatani and B. 

Hammouda, J. Appl. Cryst., (2000). v33, pp758–762. 

Contributors 

and

Collaborators 

J. D. Barnes (Polymers Division, NIST) 

R. Kolb (Exxon-Mobil Engineering R & D Ctr.) 
Polymer Characterization

56

* *

*

*

* *

* * *

*

*

* *

*

* *

^ ^ ^ ^ ^

^

^

^

^ ^ ^

^ ^ ^

^ ^ ^ ^

^

^ +

+

+

+ +

^

M236-

M335-

M227-

M188-

Partitioning of Chain 

Defects in Isotactic 

Polypropylene

David VanderHart 

In a semicrystalline, high commodity polymer like isotactic 

polypropylene (iPP), the presence of chain defects (stereo-, 

regio-, comonomer-type) can alter mechanical properties 

significantly, even at mass fractions of 1% to 2%. Properties 

can be modified, mainly by influencing the amount, size and 

perfection of its crystalline regions through controlling the 

amount and nature of chain defects. In this study, we use solid 

state NMR, computations, and an assortment of iPP’s with 

various dominant defects in order to determine the partitioning 

coefficients for 4 types of defects. 

The intent of this project is to determine experimentally, with 

supporting computations, the partitioning of various defect 

structures between the crystalline (CR) and the noncrystalline regions (NC) of isotactic polypropylene (iPP). 

IPP is a high-volume commercial polymer. Its properties can 

be modified, mainly by influencing the amount, size and 

perfection of its crystalline regions through controlling the 

amount and nature of chain defects. There are a variety of 

defect structures in commercial iPP’s and with the advent of 

metallocene catalysts, more control can be exercised with 

respect to the nature and concentrations of such defects. 

The defect types we consider are a) the most common stereo 

defect, the “stereo mrrm” defect, consisting of one methyl 

group out of stereoregular order; b) the most common regio 

defect, the “regio 2,1 erythro” defect, characterized by one 

monomer being reversed (a head-head followed by a tail-tail 

polymerization); and c) a comonomer defect where a 

comonomer (ethylene or butylene) is occasionally 

substituted for propylene during polymerization. 

Primary experimental data comes from solid state 13C NMR 

in the form of positions and intensities of unique resonances 

that can be related to the presence of each defect, along with 

a separation of those signals which originate from the CR 

regions from those arising from the NC regions of iPP. 

Data reduction involves measuring relative intensities for 

these unique resonances relative to the intensities of the iPP 

carbons and assigning the unique resonances to particular 

carbons in the defect sites within the CR lattice. To do the 

latter, “thermal annealing” followed by “energyminimization” calculations were performed for each defect in 

the CR lattice. Out of these calculations came candidate 

bond geometries for the defect chain in the vicinity of the 

chain defect. Then, ab initio chemical shift calculations were 

performed on a 7-monomer length of the central, defectcontaining chain to check calculated shifts against observed. 

Good fits then support the calculated conformations. 

25 MHz 13C spectra associated with the defects in CR regions 

are shown in Figure 1. A table summarizing the partitioning 

coefficients (PCR = ratio of CR to overall defect 

concentrations) as well as approximate conformations near 

the defects are given in Table 1. 

Figure 1: Spectra of the CR regions of the indicated iPP’s, each of which is 

dominated by a different type of defect. From the top down, the dominant defects 

are: regio-2,1-erythro, stereo-mrrm, butylene-comonomer and ethylenecomonomer. The bottom spectrum is scaled down by a factor of 20. Asterisks 

appear above each of the defect resonances, which are assigned to each dominant 

defect. The ‘^’ symbol is placed at the chemical shifts predicted from lattice-energy 

minimization followed by ab initio chemical shift calculations. For the butylenecomonomer sample, both ‘^’ and ‘+’ symbols are used to indicate those calculated 

values which belong to 2 distinct conformers that we believe to be contributing to 

the defect spectrum. Main-peak scaling varies in order to highlight defect 

resonances. 

______________

Table 1: Partitioning coefficients, approximate sequence of dihedral angles 

and our confidence level that the computations have identified the 

assignment/geometry associated with these 4 Types of defects in crystalline 

iPP.

Defect Type PCRa

 Dihedral Angle 

Sequence 

(Approximate) 

Confidence 

Level 

Regio 2,1 erythro 0.28(8) (..g+t gttt g+t..) Fair 

Stereo-mrrm 0.48(6) (..g+ttt gt g+t..) Good 

Butylene 

comonomer 

0.52(8) (..g+t g+t g+t..) 

&(..g+

t g+t g+t..)

Good 

Ethylene 

comonomer 

0.40(4) (..g+t g+t g+t..) Excellent 

a) Standard uncertainties are given in parentheses in units of the least significant 

digit. Two conformers are populated for the butylene-comonomer defect. 

Contributors 

and

Collaborators 

M. Nyden (Fire Science Division, NIST) 

R. Alamo (Department of Chemical Engineering, FAMU-FSU, Tallahassee, 

Florida) 
Polymer Characterization

57

Morphology of Ultra-thin 

Films of Semi-crystalline 

Polymers by TEM 

Catheryn Jackson 

Polymer thin films are widely used in coatings and electronics 

packaging applications. Measurements of the properties of 

amorphous thin films have shown that the properties can be 

significantly different than the bulk material, so development of 

methods to characterize thin film structure and morphology 

are vital to utilization of these materials. TEM is ideally suited 

to study semi-crystalline polymer thin films as it has both high 

resolution and electron diffraction necessary to determine 

crystallization properties in the thin film state. 

Most studies on ultra-thin films of polymers involve either 

amorphous polymers or blends of amorphous polymers. We 

were interested in using TEM to study the structure and 

morphology of semi-crystalline thin films to determine if 

crystallization could be suppressed in thin films, thereby 

forcing a semi-crystalline polymer to remain in the 

amorphous state. One prior experimental study used Fourier 

transform infrared spectroscopy to study poly(di-n-hexyl 

silane) in thin films (C. W. Frank et al., Science, 1996, 273,

912.) and measured the kinetics of crystallization to be much 

slower below film thicknesses of 20 nm. They also reported 

that crystallinity vanishes below about 15 nm in this material. 

Reports on semi-crystalline thin films of poly(ethylene oxide) 

using atomic force microscopy mostly identify dewetting 

phenomena coupled with crystallization, under these 

conditions the thickness of the film is no longer controlled 

(G. Reiter et al., J. Chem. Phys. 2000, 112, 4376.). 

We have studied thin films of isotactic polystyrene (i-PS) in 

toluene spin-coated onto carbon coated mica substrates. A 

series of discrete films of nominal thickness 5 – 60 nm were 

prepared and then floated off onto TEM grids and studied by 

electron diffraction and bright-field imaging. The as-cast 

films show no electron diffraction and are morphologically 

featureless, indicating that the i-PS is amorphous. Upon 

annealing for 12 h at 180 °C under vacuum, however, 

crystallization occurs in films greater than 15 nm thick as 

evidenced by the detection of electron diffraction and the 

morphologies shown here. Films of thickness less than about 

10 nm, however, do not crystallize upon annealing. No 

evidence of dewetting occurred in any of the amorphous or 

crystalline films studied and an AFM scratch-tip method (C. 

Ton-That et al., Langmuir 2000, 16, 2281.) is in use to 

replace the nominal film thickness estimations with measured 

values. 

The significance of this work is that we have confirmed that a 

semi-crystalline thin film can be forced into an amorphous 

state if it is thin enough and dewetting does not occur. In 

addition, we have shown that TEM is an ideal and powerful 

method to characterize the structure and morphology of semicrystalline thin film materials. 

TEM of semi-crystalline i-PS thin film (~ 40 nm) 

prepared by spin-coating from dilute toluene solution, 

after annealing at 180 °C for 12 h 

Contributors 

and

Collaborators 

W. Wallace, A. Karim (Polymers Division, NIST) 
Polymer Characterization

58

NMR Characterization of 

Nylon-6/Clay

Nanocomposites

David VanderHart, Atsushi Asano 

Exfoliated nylon-6/clay nanocomposites having about 5 % clay 

are quite popular because one achieves improvements in 

several key properties including barrier properties, fire 

retardation, modulus, and heat distortion temperature. In this 

study we a) compare different methods of dispersing the clay in 

the nylon, b) examine morphological changes arising from the 

presence of the clay, including the establishment of features 

which have a bias of proximity to the clay surface, and c) 

assess the degradation of a certain organic modifier (the

compatibilizer between nylon-6 and clay) with processing. 

Polymer manufacturers seek to develop new markets using 

existing, high-volume polymers by tailoring properties 

through processing modification, e.g., copolymerization, 

blending with another polymer or filling with solid particles. 

Nylon-6/clay nanocomposites (NnC’s) are an interesting 

example of filled polymers because the clays that are used 

are nanoparticles, being plate-like materials about 1 nm thick 

and about (0.1 to 0.5) nm wide. The two outer surfaces of 

the clay consist of silicate tetrahedra that, in turn, bound the 

central layer consisting of octahedral sites, mainly occupied 

by Al+3 with occasional Mg+2 and Fe+3 substitutions. This 

ionic character of the clay is used to compatibilize the clay 

with the polymer via the exchange of the inorganic cation for 

an organic cation (designated an ‘organic modifier’). 

Tetrasubstituted ammonium ions are often used as organic 

modifiers. Ideally, the substituents on the ammonium ion 

should be chemically stable to processing and should 

promote the mixing of nylon-6 and the clay. From an NMR 

point of view, the Fe+3 sites are also important because they 

each possess 5 unpaired electrons that make the clay strongly 

paramagnetic. These unpaired electrons have a substantial 

impact on the nuclear spins, especially those within the first 

nm of the clay surface. 

There are 2 main methods for preparing these NnC’s. One 

can either polymerize the nylon-6 in the presence of the 

organically modified clay where, typically, the organic 

modifier can be covalently incorporated into the 

polymerizing chains. Or one can simply melt-blend, with 

vigorous mixing, the organically modified clay with the 

whole polymer. 

We were able to show that, compared to melt crystallized 

nylon-6, the nylon-6 in these NnC’s, with nominal mass 

fractions 5 % clay, had a very similar crystallinity, very 

similar crystallite size, yet a dominant γ-crystal form relative 

to the α-form that is typical of nylon-6. The clay nucleates 

the γ-form of nylon-6 and at melt-cooling rates of 1 °C/min, 

greater than 90 % of the crystallites are of the γ-form, 

regardless of whether one uses in situ-polymerized NnC’s or 

melt-blended NnC’s. 

Processing NnC’s usually implies that the viscosity of the 

melt is higher than would apply to the pure polymer; hence, 

there is a tendency to process at temperatures higher than 

would normally be used for the pure polymer. For an in situpolymerized polymer that was injection molded at 295 °C, 

we found a reduced ability both to nucleate the γ-phase 

during melt crystallization and to retain this γ-form upon 

annealing for several hours at 213 °C. For these injection 

molded samples, whose melt crystallization history involved 

relatively rapid cooling, a mixture of the α- and γ- crystal 

forms were found. However, using the paramagnetic 

character of the clay as an additional source of relaxation for 

proton spins, it was ascertained that the average proximity of 

the γ-crystallites from the clay surfaces was only slightly 

higher than that of the α-crystallites. This is surprising 

because the clay preferentially nucleates the γ-phase. 

However, when these samples are annealed at 213 °C, the 

fraction of the crystallites in the α-form increases and the 

morphology is transformed into a highly stratified 

morphology with the γ crystallites near the clay surfaces and 

the α crystallites in the more distant, intervening spaces. 

The proton relaxation induced by the paramagnetism of the 

clay also provided the justification for claiming that the 

average proton longitudinal relaxation time, T1

H, measured at 

a given magnetic field strength, will provide a relative 

ranking of the quality of clay dispersion in a set of dry NnC 

samples that is formulated with the same clay, the same 

clay/polymer stoichiometry, and the same crystallization 

history. That claim is supported experimentally; the shorter 

T1

H’s correspond to the better clay dispersions. 

Finally, in certain cases of the blended NnC’s, we could 

follow the extent of and the chemistry of chemical 

degradation of the organic modifier (OM). For example, 

when the nylon and the clay are mixed at 240 °C, the 

tetraalkylammonium ion, Me2T2N+

, (Me = methyl and T = 

hydrogenated tallow ≈ C17H35) degrades to the free amine, 

MeT2N, which then phase separates and moves away from 

the clay surface into the polymer matrix. Interestingly, the 

amount of degradation is correlated with the combination of 

higher temperature and mechanical stress, as opposed to 

temperature alone. 

Contributors 

and

Collaborators 

J. Gilman (Fire Science Division, NIST) 

D.L. Hunter (Southern Clay Products) 
Polymer Characterization

59

Real-Time Monitoring of 

Biaxial Stretched Film 

Anthony Bur 

The molecular orientation and the temperature at which they 

are stretched determine the performance properties of biaxially 

stretched films. Film processors measure orientation in post 

processing quality control experiments that are carried out 

with a considerable time delay after processing. A method for 

in-line, real-time monitoring of orientation and temperature is 

needed to avoid costly time delays and rejected product runs. 

To address this need, we have developed a fluorescence 

anisotropy sensor for real-time monitoring of fluorescent 

anisotropy and temperature during biaxial stretching of film. 

Polymer film manufacturing consists of biaxially stretching 

an extruded strip of resin until a film of desired thickness is 

achieved. The applied extensional stress, if carried out at the 

appropriate temperature, causes significant molecular 

orientation. This orientation is the basis for film integrity and 

its performance properties. Real-time, on-line measurements 

of anisotropy and temperature are desirable, not only because 

they avoid post processing characterization, but also because 

they can be used to monitor film conditions, to detect 

problems with processing parameters and for process control. 

To carry out fluorescence anisotropy measurements a 

fluorescent dye is incorporated in the polymer by mixing dye 

and resin at low levels of dye concentration, less than 10-5

mass fraction of dye in the resin. A dye with asymmetric 

geometrical structure is chosen because it will orient under 

the influence of extensional stress. A molecule that we use 

for this measurement is bis(di-tert-butylphenyl)-perylene 

dicarboximide (BTBP). 

The anisotropy measurement employs excitation light 

polarized with a fixed spatial relationship with respect to the 

principal orientation axis of the film or sheet. Orientation 

factors are obtained from the emitted fluorescent light, which 

is analyzed for its polarization. Fluorescence anisotropy, r, is 

defined as r

I I

I I

vv vh

vv vh

= −

+ 2

where Ivv and Ivh are respectively 

vertically and horizontally polarized fluorescent light which 

are produced by vertically polarized excitation light. For our 

application v corresponds to the machine direction and h to 

the transverse direction. 

The NIST sensor head contains optics for polarizing the 

excitation light and analyzing fluorescence polarization. It 

can be conveniently mounted adjacent to an extruded film or 

sheet for real-time monitoring, or for acquiring area scans of 

fluorescence anisotropy. The sensor head has been 

constructed and interfaced with computer and detection 

equipment. 

The sensor has been installed at a Mobil Chemical Co. 

production line facility where it is positioned in a tenter oven 

on a traversing rail that will allow scans of temperature and 

anisotropy of biaxially stretched polypropylene films. 

Using this sensor, the specimen can be excited with either 

vertical or horizontal polarized light, so that biaxial 

orientations in the machine and transverse directions can be 

measured. The temperature measurement is obtained from 

the fluorescence spectrum by measuring the ratio of 

fluorescence intensities from BTBP at 544 nm and 577 nm. 

The area scan shown below is for a biaxially stretched film of 

polypropylene with a relatively low stretch ratio of 2.5. In 

production, the stretch ratios reach 7.5. The blue color at 45o

corresponds to low anisotropy (r ≈ 0.2) and the red/orange 

color is for r ≈ 0.34. The scanned area is (40 by 50) mm. 

The standard uncertainty in the measurement is ± 0.005 mm. 

Contributors 

and

Collaborators 

A. Bur, S. Roth (Polymers Division, NIST) 

M. Amon (Mobil Chemical Co.) 

or Ihh and Ihv detection 

bifurcated optical fibers

for Ivv and Ivh detection

calcite polarizer

lenses

mirror

polarized excitation light

optical fiber

for temperature

measurement

0 12 25 38

38

25

12

0

col

0.225 0.250 0.275 0.300 0.325

_451BI_TXT_3_md

X

Y

P O L A R IZ A T IO N
Polymer Characterization

60

Extrusion Visualization 

Facility Sheds Light on 

Processing

Kalman Migler 

The polymer processing industry seeks better methods to 

evaluate the behavior of resins during manufacture. The NIST 

extrusion visualization facility allows unprecedented access to 

monitor the micro-scale morphological development during 

polymer processing. The flexible optics allow for a variety of 

applications including flow velocimetry, monitoring of blend 

structure, quality assurance and additive behavior. 

We have developed optical based technologies for in-line 

measurements during polymer processing. As described 

below, applications of the technology include velocimetry 

and slippage, quality control, and morphological 

measurements of blends, fibers and dispersions. 

Two different flow cells have been used. The first one, called 

an optical slit die, is show below. It is located at the exit of a 

twin-screw extruder. Molten polymer travels through either 

the horizontal slit or the vertical bypass valve. Two 

transparent sapphire windows are flush mounted on opposite 

sides of the slit. (In the figure below, only the top window is 

visible.) This provides access for the optical instrumentation. 

A second flow cell is based on flow through a round 

transparent tube. 

We conduct our studies in both real space through optical 

microscopy and in reciprocal space through optical light 

scattering. The optical microscopy is useful for structures 

larger than approximately 1 μm, whereas the optical light 

scattering gives indirect information about structures that are 

as small as 0.1 μm. The optical hardware is configured for 

rapid switching between these two modes of operation so that 

nearly simultaneous measurements may be conducted. 

The first use that we demonstrate is particle-tracking 

velocimetry. We track either intentionally imbedded 

particles, such as 10 μm silica, or the naturally occurring 

impurities in the material. 

The above figure shows the velocity from one wall to the 

other. The velocity is zero at both walls and becomes a 

maximum in the center. As the throughput is increased, we 

see a transition from parabolic flow at low throughput, to plug 

like flow at high. Elsewhere in this report we highlighted 

current work regarding sharkskin and flow profiles. 

A second use of the facility is for the determination of 

structure during processing. The figure below shows the case 

of a polystyrene/polyethylene (PS/PE) blend as it flows 

through the slit die. At low shear (left column) the minor 

component (PS) is nearly spherical as seen by both 

microscopy (bottom) and light scattering (top). At 

intermediate throughput, the PS is strongly elongated into 

string-like structures. At the highest throughput, the 

morphology reverts to the spherical droplets. 

A variety of systems have been studied with the extrusion 

visualization facility, including liquid crystal polymer blends 

and reactive systems. 

Contributors 

and

Collaborators 

K. Migler, K. Flynn, F. Qiao, C. Han, E. Hobbie (Polymers Division, NIST) 

C. Lavallée (3M Canada Company) 

C.L. Gettinger, V.P Thalacker (3M Company) 

M. Dillon, S.S. Woods (Dyneon LLC) 

Slit Die

Polymer

10

8

6

4

2

0

v

x(y) (m

m

/

s)

0.0 0.1 0.2 0.3 0.4

y (m m )
Polymer Characterization

61

“Superstring” Structures 

during Micro-Scale 

Processing

Kalman Migler 

Manufacturers of medical and optical devices are under 

increasing pressure to miniaturize their components. 

However, the concepts and practices that are commonly used 

in macro-scale fabrication may need to be significantly altered 

when working at smaller length scales. Here we explore the 

breakdown of fundamental principles of polymer blends mixing 

that occur when the part size scale becomes small. 

Polymer blends are traditionally used in macroscopic 

applications where the synergetic properties of two 

immiscible polymers can be exploited, such as in nylon / 

rubber blends. The length scale of the dispersed phase is 

typically of order 0.3 μm whereas the length scale of the part 

manufactured from the blend is much larger (e.g., a car 

bumper). There is current interest in micro and nano length 

scale technologies in which polymer blends could play an 

important role, but the physics of processing polymeric 

emulsions when the droplet size is comparable to a sample 

dimension is poorly understood. Here we report on several 

novel phenomena that occur in this regime. 

The size and morphology of the dispersed component is 

determined during material processing and is crucial to the 

final physical properties; for example, fibers can provide 

great enhancements in unidirectional strength, sheet 

structures can possess ultra-low permeability and spherical 

inclusions provide impact resistance. 

Here, we shear a polymer blend between two transparent 

plates and examine the structures as a function of the width 

of the gap between the shearing plates. It is well known that 

there is a maximum stable size for droplets of one component 

dispersed in a matrix of a second component. We have 

discovered a transition between droplets at high shear and 

strings at low shear that occurs when the size of the dispersed 

droplets becomes comparable to the gap width between the 

shearing surfaces (illustration on lower left). The transition is 

abrupt and proceeds via the coalescence of droplets in a four 

stage kinetic process (below). Once formed, the strings are 

stable and exhibit pronounced hysteresis. 

These experiments were conducted on custom built precision 

instrumentation that was developed in the Polymers Division 

for the study of polymer blends under shear. The apparatus 

allows for nearly simultaneous optical microscopy and light 

scattering to visualize blend structure over a wide range of 

length scales. 

There are intriguing possible applications of this technology. 

If the string component was conductive and the matrix was 

an insulator with good mechanical properties, then one could 

produce wires. If the processing was done at elevated 

temperature and the string component formed into a fiber, 

one could have ultra-thin materials of high one-dimensional 

strength. A third application would be to dissolve out the 

string component and use the resulting structures as scaffolds 

in tissue engineered products. 

Contributors 

and

Collaborators 

K. Migler, C. Han (Polymers Division, NIST) 

t = -0.5 s t = 45 s

t = 98 s t = 500 s
Polymer Characterization

62

Interfaces in Fiber 

Reinforced Polymer 

Composites

Joseph Lenhart, Richard Parnas 

Manufacturers of fiber-reinforced composites seek to improve 

properties by manipulating the interface between 

reinforcement and matrix. However, there are no suitable 

methods to probe the chemical and physical characteristics 

owing to the small size and inaccessibility of the buried 

interface. We developed a technique to probe the structure of 

buried interfacial regions relevant to glass fiber reinforced 

composites by localizing a viscosity sensitive fluorescent dye 

on the substrate surface. Through use of optical fiber methods 

interface measurements may be made on buried interfaces. 

A dimethylaminonitrostilbene fluorophore was tethered to a 

triethoxy silane coupling agent, generating a fluorescently 

labeled silane coupling agent (FLSCA). 

Glass surfaces were coated with silane coupling agent multilayers that were doped with small levels of the FLSCA 

molecule. The silane-coated glass was then immersed in 

epoxy resin and the resin cured. A blue shift in FLSCA 

emission and an increase in the emission intensity could be 

followed during resin cure, illustrating the probe sensitivity 

to interfacial cure. The emission maximum from FLSCA 

grafted to the glass surface was different than when FLSCA 

was dissolved into bulk epoxy resin, suggesting a different 

interfacial structure. 

When the dye was dissolved into bulk cured resin, a distinct 

break in the fluorescence maximum verses temperature slope 

was detected at the glass transition of the bulk epoxy. 

Similar breaks were observed from the grafted FLSCA 

layers, illustrating sensitivity of the localized probe to the 

buried interfacial glass transition. The temperature of the 

interfacial transition was dependent on the initial structure of 

the grafted silane coupling agent layer. Physically adsorbed 

material from the unwashed silane coupling agent layers 

generated a zone of plasticized polymer in the buried 

interface, leading to a lower interfacial transition 

temperature. 

Washed layers were tightly bound to the glass surface, 

restricting the polymer motion in the interfacial region and 

raising the interfacial transition temperature. For the figure 

above, the glass transition of the bulk resin was (85 ± 3) o

C. 

This was the first measurement of a glass transition 

temperature in sub-micrometer buried polymer / substrate 

interfacial regions. The work was recently published in J. 

Coll. Interface Sci. 221, 75, 2000 and Langmuir 16, 8145, 

2000 and another article was submitted to Macromolecules. 

A proceedings paper for the Society of Plastics Engineers 

Annual Conference in Orlando FL (May 2000) won the best 

paper award in the Thermoset Division. 

The technique can be made practical for monitoring resin 

cure and interfacial development during composite 

manufacturing by grafting the FLSCA layers to a glass fiber 

optic. The fiber optic can be inserted into the composite 

mold and measurements made in-situ during processing. 

Contributors 

and

Collaborators 

 J. Lenhart, J. Dunkers, R. Parnas (Polymers Division, NIST) 

 J. van Zanten (North Carolina State University) 

Si (CH2) (H5C2O)3 3 NC O

O

H

(CH CH3 2) N

NO2

(CH2)5

DMANS

fluorophore

Triethoxy

silane 

coupling agent

FLSCA

Temperature (oC)

30 40 50 60 70 80 90 100 110 120 130 140

Emission Maximum (nm)

584

586

588

590

592

594

596

598

600

602

604

unwashed layer

washed layer
Polymer Characterization

63

Fiber Optic Flow and 

Cure Sensing for Liquid 

Composite Molding 

Joy Dunkers, Joseph Lenhart 

Major advantages of polymer matrix composites include a high 

strength-to-weight ratio, corrosion resistance, and thermal and 

electrical insulating properties. However, the cost of polymer 

matrix composites must be reduced to be competitive in 

consumer markets. One strategy is to decrease manufacturing 

cost through process optimization and reduction of scrap. The 

introduction of fiber optic sensors into the liquid composite 

molding (LCM) process for flow and cure monitoring provides 

a non-invasive means of obtaining real time information on 

mold filling and resin cure for control decisions. 

Under typical composite manufacturing circumstances, it is 

difficult to detect if the resin is saturating the preform. 

Embedded sensors can help monitor the impregnation process. 

For the first time, long period gratings (LPGs) will be used as 

embedded flow monitoring sensors in LCM to detect the arrival 

of resin in the mold during filling. LPGs are similar to Bragg 

gratings, but function differently because they are used to couple 

light out of the core. LPGs have a grating periodicity of 

typically (130 to 150) μm. When the higher index resin covers a 

LPG sensor, the light that would have been attenuated gets 

coupled back into the core and, hence, the dip in the 

transmission spectrum disappears. Resin flow-front information 

is very useful to composite manufacturers because it alerts them 

to specific problems that occur during resin injection. 

The figure below shows a typical spectrum of an optical fiber 

with two LPGs written on it. The vertical axis is relative 

intensity with respect to the maximum intensity detected by the 

system for that particular scan. In this case, the LPGs were 

written such that light at 1509 nm and 1549 nm would be 

filtered out, as evident from the transmission dips seen in that 

figure. These dips disappear when the resin covers one sensor, 

coupling the light at 1509 nm back into the core-propagating 

mode. When both LPGs are covered, the spectrum is like that of 

an optical fiber without any LPGs written on it. Since each of 

the LPGs is written at distinctly different wavelengths, it is 

possible to identify where and when the sensors are covered. 

Fluorescence has been used to monitor resin cure when the 

dye is dissolved in the bulk resin. This can create problems in 

a manufacturing environment. First, an extra processing step 

may be required to mix the dye into the resin. Second, the 

dye can drastically change the resin color. Finally, the 

fluorescence response comes from the bulk polymer and the 

behavior of the fiber / resin interface is ignored. Even if 

evanescent wave techniques are used, the evanescent wave 

can still propagate a micrometer or more into the resin, and 

much of the sensor response will be from the bulk resin. 

A fluorescent probe molecule has been tethered to a triethoxy 

silane-coupling agent, generating a fluorescently labeled 

silane coupling agent molecule (FLSCA). To obtain an 

interfacial sensitive response, silane coupling agent chemistry 

is then used to graft FLSCA to a high refractive index glass 

fiber optic. 

When the fiber optic is immersed in epoxy resin, an increase 

in fluorescence intensity and a blue shift in the fluorescence 

emission can be monitored during resin cure. 

The fiber optic LPGs sensor was successfully demonstrated 

in an industrial vacuum assisted resin transfer molding 

operation at WebCore in Dayton, OH. 

Contributors 

and

Collaborators 

J. Lenhart, J. Dunkers R. Parnas (Polymers Division, NIST) 

S. Kueh, S. Advani (University of Delaware) 

J. van Zanten (North Carolina State University) 

P. Furrow, M. Jones (F&S/Luna Innovations) 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1490 1510 1530 1550 1570 1590

Wavelength (nm)

Relative Intensity

(a) Clean

(b) 1509nm LPG covered

(c) Both LPGs covered

Excitation beam

Evanescent

wave

Fluorescent

Emission

Glass fiber optic Fluorescent response

Resin polymer network

Fluorescent dye molecule

LPG2 

LPG1 
Publications

64

Polymers Division Publications 

Alamo, R. G.; Isasi, J. R.; Kim, M. H.; Mandelkern, L., and 

Vanderhart, D. L.,"Thermal and Structural Behavior of 

Metallocene-Type Random Propylene Copolymers", 

Abstracts of Papers of the American Chemical Society 

1999 Aug 22; 218:244-PMSE. 

Alamo, R. G.; Vanderhart, D. L.; Nyden, M. R., and 

Mandelkern, L.,"Morphological Partitioning of Ethylene 

Defects in Random Propylene-Ethylene Copolymers", 

Macromolecules 2000 Aug 8; 33(16):6094-6105. 

Allegrini, P.; Douglas, J. F., and Glotzer, S. C.,"Dynamic 

Entropy as a Measure of Caging and Persistent Particle 

Motion in Supercooled Liquids", Physical Review E 1999 

Nov; 60(5):5714-5724. 

Amis, E. J.; Bauer, B. J.; Topp, A.; Groehn, F.; Prosa, T. J.; 

Viers, B. D.; Liu, D. W.; Barnes, K. A.; Jackson, C. L.; 

Nisato, G.; Karim, A., and Douglas, J. F., " Preparation 

and Characterization of Polymer/Dendrimer Blends - Final 

Report, March 2000", NISTIR 6506; 2000. 

Amis, E. J. and Fanconi, B. M., " Polymers Division 

Technical Activities - 1999", NISTIR 6435; 1999. 

Antonucci, J. M.; Skrtic, D., and Eanes, E. D.,"Polymer 

Matrix Effects on the Properties of Amorphous Calcium 

Phosphate-filled Composites", Polymer Preprint (ACS 

Natl. Mtg., Washington, DC, August 2000) 2000. 

Antonucci, J. M.; Stansbury, J. W., and Fowler, B. O., "Ethyl 

α-Hydroxymethylacrylate, A Novel Isomeric Analog of 2-

Hydroxyethyl Methacrylate (HEMA)", Transactions of 

6th World Biomaterials Congress; Kameuela, HA. 

---,"An Improved Synthesis of Ethyl αHydroxymethylacrylate, a Unique Isomeric Analog of 

HEMA. ", Proc. of the ACS Natl. Mtg., Wash., DC, 

August 2000 2000. 

---,"Synthesis and Characterization of Ethyl α - 

Hydroxymethylacrylate, a Novel Isomeric Analog of 

HEMA.", Journal of Dental Research 2000; 79:30. 

Atalla, R. H. and Vanderhart, D. L.,"The Role of Solid State 

C-13 NMR Spectroscopy in Studies of the Nature of 

Native Celluloses", Solid State Nuclear Magnetic 

Resonance 1999 Oct; 15(1):1-19. 

Barnes, J. D.; Fanconi, B. M., and Amis, E. J., " 

POLYMER99 - NIST Polymers Division Published Works 

for 1999", NISTIR/CD2000. 

Barnes, J. D.; Kolb, R.; Barnes, K. A.; Nakatani, A. I., and 

Hammouda, B.,"Microstructure Analysis Using 

Temperature-Induced Contrast Variation in Small-Angle 

Scattering", Abstracts of Papers of the American Chemical 

Society 1999 Aug 22; 218:265-PMSE. 

Barnes, K. A.; Douglas, J. F.; Liu, D. W.; Bauer, B.; Amis, E. 

J., and Karim, A.,"Influence of Generation Number on the 

Dewetting of Hypergraft Poly(2-Ethyl-2-Oxazoline) 

Films", Polymer International 2000 May; 49(5):463-468. 

Barnes, K. A.; Karim, A.; Douglas, J. F.; Nakatani, A. I.; 

Gruell, H., and Amis, E. J.,"Suppression of Dewetting in 

Nanoparticle-Filled Polymer Films", Macromolecules 

2000 May 30; 33(11):4177-4185. 

Bauer, B. J. and Amis, E. J., " Characterization of 

Dendritically Branched Polymers by SANS, SAXS, and 

TEM", in Dendritic Polymers, ed.: Tomalia, D. A. and 

Frechet, J. M. J.; in press. 

Bauer, B. J.; Ramzi, A.; Liu, D. W.; Scherrenberg, R. L.; 

Froehling, P., and Joosten, J.,"Blends of Fatty-AcidModified Dendrimers With Polyolefins", Journal of 

Polymer Science Part B-Polymer Physics 2000 Jan 1; 

38(1):95-100. 

Blair, W. R.; Guttman, C. M., and Guiseppetti, A. A.,"Surface 

Morphology Variations in MALDI-TOF-Mass 

Spectrometry Samples Prepared by Various Techniques 

Examined by Scanning Electron Microscopy", Proc. of the 

48 th ASMS Conf. on Mass Spectrometry and Allied 

Topics. 2000. 
Publications

65

Bloss, P.; Dereggi, A. S.; Glasel, H. J.; Hartmann, E.; Hirsch, 

D., and Schafer, H.,"Polarization Distribution in CeramicPolymer Nanocomposites", Journal of Applied Physics 

1999 Sep 1; 86(5):2712-2718. 

Bloss, P.; DeReggi, A. S., and Schafer, H.,"Electric Field 

Profile and Thermal Properties in Substrate-Supported 

Dielectric Films", Phys. Rev. B 2000 Sep 15; 62(12):8517-

8530.

Bloss, P.; Dereggi, A. S.; Yang, G. M.; Sessler, G. M., and 

Schafer, H.,"Thermal and Acoustic Pulse Studies of SpaceCharge Profiles in Electron-Irradiated Fluoroethylene 

Propylene", Journal of Physics D-Applied Physics 2000 

Feb 21; 33(4):430-436. 

Bowen, R. L.; Farahani, M.; Dickens, S. H., and Guttman, C. 

M.,"MALDI ToF MS Analysis of a Library of 

Polymerizable Cyclodextrin Derivatives", Journal of 

Dental Research 2000 Apr; 79(4):905-911. 

Briggman, K. A.; Richter, L. J.; Stephenson, J. C., and 

Wallace, W. E.,"Structure of Thin Polymer Film Interfaces 

Using Broadband Vibrationally Resonant Sum-Frequency 

Generation", Abstracts of Papers of the American 

Chemical Society 2000 Mar 26; 219:362. 

Bu, Z. M.; Neumann, D. A.; Lee, S. H.; Brown, C. M.; 

Engelman, D. M., and Han, C. C.,"A View of Dynamics 

Changes in the Molten Globule-Native Folding Step by 

Quasielastic Neutron Scattering", Journal of Molecular 

Biology 2000 Aug 11; 301(2):525-536. 

Bur, A. J. and Roth, S. C., "Fluorescence Based Temperature 

Measurements and Applications to Real-Time Polymer 

Processing", Proc. of the Society of Plastics Engineers 

Annual Technical Meeting; Orlando, FL. 

Bur, A. J.; Roth, S. C., and Thomas, C. L.,"Fluorescence 

Anisotropy Sensor and Its Application to Polymer 

Processing and Characterization", Review of Scientific 

Instruments 2000 Mar; 71(3):1516-1523. 

Bur, A. J. and Thomas, C. L., "An Optical Sensor for Polymer 

Injection Molding", Proc. of the 197th Electrochemical 

Society Meeting; Toronto, Canada. 

Cerrada, M. L. and Mckenna, G. B.,"Physical Aging of 

Amorphous PEN: Isothermal, Isochronal and Isostructural 

Results", Macromolecules 2000 Apr 18; 33(8):3065-3076. 

Chiang, C. K.; Popielarz, R.; Nozaki, R., and Obrzut, J., 

"Broadband Dielectric Relaxation of Polymer Composite 

Films", Organic/Inrganic Hybrid Materials 2000; San 

Francisco, CA. 

Chiang, C. K.; Wallace, W. E.; Lynn, G. W.; Feiler, D., and 

Xia, W.,"Thermally Induced Stress Relaxation and 

Densification of Spin- on-Glass Thin Films", Applied 

Physics Letters 2000 Jan 24; 76(4):430-432. 

Chiang, M. Y. and Fernandez-Garcia, M., "Effect of 

Hygrothermal Aging History on Swelling and Tg in a 

Commercial Adhesive", Proc. of the 23rd Annual Meeting 

of The Adhesion Society. 

Chiang, M. Y. M.; Fernandez-Garcia, M., and Yorkgitis, E. 

M., "Effect of Water Exposure Cycles on Physical 

Properties of a Particle-Filled, Epoxy-Based Adhesive", 

Proc. of SAMPE 2000 Meeting. 

Choi, S.; Briber, R. M.; Bauer, B. J.; Liu, D. W., and Gauthier, 

M.,"Small-Angle Neutron Scattering of Blends of 

Arborescent Polystyrenes", Macromolecules 2000 Aug 22; 

33(17):6495-6501. 

Choi, S.; Briber, R. M.; Bauer, B. J.; Topp, A.; Gauthier, M., 

and Tichagwa, L.,"Small-Angle Neutron Scattering of 

Solutions of Arborescent Graft Polystyrenes", 

Macromolecules 1999 Nov 16; 32(23):7879-7886. 

Chou, K. F.; Han, C. C., and Lee, S.,"Water Transport in 2-

Hydroxyethyl Methacrylate Copolymer Irradiated by 

Gamma Rays in Air and Related Phenomena", Journal of 

Polymer Science Part B-Polymer Physics 2000 Mar 1; 

38(5):659-671. 

---,"Water Transport in Crosslinked 2-Hydroxyethyl 

Methacrylate", Polymer Engineering and Science 2000 

Apr; 40(4):1004-1014. 

Dereggi, A. S.; Balizer, E.; Neumann, D. A., and Bateman, F., 

"Electrostriction Mechanism in Electron-Irradiated 

Ferroelectric Copolymer: A. Frequency Response Model", 

Conference on Electrical Insulation and Dielectric 

Phenomena. 

Donati, C.; Glotzer, S. C.; Poole, P. H.; Kob, W., and 

Plimpton, S. J.,"Spatial Correlations of Mobility and 

Immobility in a Glass- Forming Lennard-Jones Liquid", 

Physical Review E 1999 Sep; 60(3):3107-3119. 
Publications

66

Douglas, J. F.; Kent, M. S.; Satija, S. K., and Karim, 

A.,"Swelling of Grafted Polymer "Brushes"", 

Encyclopedia of Materials: Science and Technology in 

press. 

Dudowicz, J.; Freed, K. F., and Douglas, J. F.,"Lattice Model 

of Living Polymerization. I. Basic Thermodynamic 

Properties", Journal of Chemical Physics 1999 Oct 15; 

111(15):7116-7130. 

---,"Lattice Model of Living Polymerization. II. Interplay 

Between Polymerization and Phase Stability", Journal of 

Chemical Physics 2000 Jan 8; 112(2):1002-1010. 

---,"Lattice Model of Living Polymerization. III. Evidence for 

Particle Clustering From Phase Separation Properties and 

"Rounding" of the Dynamical Clustering Transition", 

Journal of Chemical Physics 2000 Jul 1; 113(1):434-446. 

Dunkers, J. P.; Everett, M. J.; Sanders, D. P., and Hunston, D. 

L., "Imaging of Composite Defects and Damage Using 

Optical Coherence Tomography", Proc. of PLAST, 

Advancing with Composites 2000; Milan, Italy. 

Dunkers, J. P.; Labazzo, K. S.; Kohn, J, and Parnas, R. 

S.,"Optical Coherence Tomography for Imaging Tissue 

Scaffolds", NISTIR 6535 2000; 25-30. 

Dunkers, J. P.; Lenhart, J. L.; Kueh, S. R.; van Zanten, J. H.; 

Advani, S. G., and Parnas, R. S., "Fiber Optics Flow and 

Cure Sensing for Liquid Composite Molding", Proc. of the 

Intl. Conf. on Trends in Optical Nondestructive Testing ; 

Lugano, Switzerland. 

Dunkers, J. P.; Phelan, F. R.; Sanders, D. S.; Everett, M. J.; 

Green, W. H.; Hunston, D. L., and Parnas, R. S.,"The 

Application of Optical Coherence Tomography in 

Problems in Polymer Matrix Composites", Journal of 

Optics and Lasers in Engineering in press. 

Dunkers, J. P.; Sanders, D. S.; Hunston, D. L., and Everett, M. 

J., "Imaging of Impact Damage in Composites Using 

Optical Coherence Tomography", Proc. of the 23rd Annual 

Meeting of The Adhesion Society; Blacksburg, VA. 

Evmenenko, G.; Bauer, B. J.; Kleppinger, R.; Forier, B.; 

Dehaven, W.; Amis, E. J.; Miscehnko, N., and Reynaers, 

H.,"The Influence of Molecular Architecture and Solvent 

Type on the Size of Structure of Poly(benzyl ether) 

Dendrimers by SANS", Physica B 2000 Mar; 276:349-

350.

Ferreiro, V.; Douglas, J. F.; Coulon, G., and Karim, 

A.,"Atomic Force Microscopy Studies of Phase Ordering 

in Polymer Blends and Clay-Filled Systems", ACS 

Polymer Preprint 2000. 

Fitzpatrick, K. T.; Antonucci, J. M., and Schumacher, G. 

E.,"Effect of Photoinitiator Concentration in a Dentin 

Bonding System", Journal of Dental Research 2000; 

79:849. 

Franz, S.; Donati, C.; Parisi, G., and Glotzer, S. C.,"On 

Dynamical Correlations in Supercooled Liquids", 

Philosophical Magazine B-Physics of Condensed Matter 

Statistical Mechanics Electronic Optical and Magnetic 

Properties 1999; 79(11-12):1827-1831. 

Friedman, H. L.; Johnson, R. A.; Gusev, V.; Neimark, A. V.; 

Buvel, D.; Salem, D. R., and Parnas, R. S.,"Visualization 

and Quantification of Forced in-Plane Flow Through 

Deformed Porous Media", Polymer Composites 1999 Oct; 

20(5):613-627. 

Gilman, J. W.; Harris, R. H.; Jackson, C. L.; Morgan, A. B.; 

Brassell, L. D., and Hunter, D. L.,"Phenolic Cyanate Ester 

Clay Nanocomposites: Effect of Ammonium Ion Structure 

on Flammability and Nanodispersion", ACS PMSE 

Preprints 2000 Mar 26; 82:276. 

Gilman, J. W.; Jackson, C. L.; Morgan, A. B.; Harris, R.; 

Manias, E.; Giannelis, E. P.; Wuthenow, M.; Hilton, D., 

and Phillips, S. H.,"Flammability Properties of Polymer - 

Layered-Silicate Nanocomposites. Polypropylene and 

Polystyrene Nanocomposites", Chemistry of Materials 

2000 Jul; 12(7):1866-1873. 

Gilman, J. W.; Kashiwagi, T.; Morgan, A. B.; Harris, R. H.; 

Brassell, L.; VanLandingham, M., and Jackson, C. L., " 

Flammability of Polymer Clay Nanocomposites 

Consortium: Year One Annual Report", NISTIR 6531; 

2000 Jul. 

Glotzer, S. C.,"Spatially Heterogeneous Dynamics in Liquids: 

Insights From Simulation", Journal of Non-Crystalline 

Solids 2000 Sep; 274(1-3):342-355. 

Glotzer, S. C.; Jans, N., and Poole, P. H.,"The Potential 

Energy Landscape of the +/- J Ising Spin Glass", Journal 

of Physics-Condensed Matter 2000 Jul 24; 12(29):6675-

6682.
Publications

67

Glotzer, S. C.; Novikov, V. N., and Schroder, T. B.,"TimeDependent, Four-Point Density Correlation Function 

Description of Dynamical Heterogeneity and Decoupling 

in Supercooled Liquids", Journal of Chemical Physics 

2000 Jan 8; 112(2):509-512. 

Glotzer, S. C. and Starr, F. W.,"Multiscale Modeling of Filled 

and Nonofilled Polymers", Proc. of Foundations of 

Molecular Modeling and Simulation 2000. 

Goldschmidt, R. J. and Guttman, C. M., "Matrix Clusters and 

Polymer-Matrix Adducts in the MALDI Analysis of 

Polystyrene", Proc. of the 48th ASMS Conf. on Mass 

Spectrometry and Allied Topics.; Long Beach, CA. 

---,"Response Saturation of Polystyrene in MALDI", Abstracts 

of Papers of the American Chemical Society 2000 Mar 26; 

219:53-POLY. 

Goldschmidt, R. J.; Wetzel, S. J.; Blair, W. R., and Guttman, 

C. M.,"Post-Source Decay in the Analysis of Polystyrene 

by Matrix-Assisted Laser Desorption/Ionization Time-ofFlight Mass Spectrometry", J. of the American Society for 

Mass Spectrometry 2000; 11:1095-1106. 

Groehn, F.; Akpalu, Y. A.; Bauer, B. J., and Amis, E. 

J.,"Organic-inorganic Hybrid Structures with Dendrimers: 

A Small Angle X-ray Scattering Study on a Mesoscopic 

Model System", 1999 National Synchrotron Light Source 

Activity Report 2000. 

Groehn, F.; Bauer, B. J.; Akpalu, Y. A.; Jackson, C. L., and 

Amis, E. J.,"Dendrimers as Templates for the Formation of 

Inorganic Nanoclusters", Macromolecules in press. 

Groehn, F.; Bauer, B. J., and Amis, E. J., "Organic-Inorganic 

Hybrid Particles by Dendrimer Nanotemplating", Proc. of 

the Materials Research Society Mtg; San Francisco. 

Gröhn, F.; Bauer, B. J.; Akpalu, Y. A.; Jackson, C. L., and 

Amis, E. J.,"Dendrimer Templates for the Formation of 

Gold Nanoclusters", Macromolecules 2000 Aug 8; 

33(16):6042-6050. 

Grohn, F.; Bauer, B. J., and Amis, E. J.,"Templating 

Nanocrystals With Dendrimers: a Mesoscopic Model 

System", Abstracts of Papers of the American Chemical 

Society 2000 Mar 26; 219:295-POLY. 

Guttman, C. M.; Maurey, J. R., and Blair, W. R., " 

Certification of the Relative Molecular Mass and the 

Limiting Viscosity of SRM 2886, a Polyethylene of 

Narrow Molecular Mass Distribution", NISTIR 6487; 

2000.

Guttman, C. M.; Maurey, J. R.; Blair, W. R., and Schultheisz, 

C. R., " Certification of the Relative Molecular Mass and 

the Limiting Viscosity of SRM 2887, a Polyethylene of 

Narrow Molecular Mass Distribution ", NISTIR 6456; 

2000.

Guttman, C. M.; Maurey, J. R., and Blair, W. R. Schultheisz 

C. R., " Certification of the Relative Molecular Mass and 

the Limiting Viscosity of SRM 2885, a Polyethylene of 

Narrow Molecular Mass Distribution ", NISTIR 6454; 

2000.

Guttman, C. M.; Wetzel, S. J.; Blair, W. R.; Fanconi, B. M.; 

Girard, J. E.; Goldschmidt, R. J.; Wallace, W. E., and 

VanderHart, D. L.,"National Institute of Standards and 

Technology Sponsored Interlaboratory Comparison of 

Polystyrene Molecular Mass Distribution Obtained by 

Matrix Assisted Laser Desorption Ionization Time-ofFlight Mass Spectrometry: Statistical Analysis", 

Analytical Chemistry in press. 

Guttman, C. M.; Wetzel, S. J.; Wallace, W. E.; Blair, W. R.; 

Goldschmidt, R. M.; Vanderhart, D., and Fanconi, B. 

M.,"Determination of the Molecular-Mass Distribution of 

a Narrow Polydispersity Polystyrene by MALDI ToF MS: 

Interlaboratory Comparison", Abstracts of Papers of the 

American Chemical Society 2000 Mar 26; 219:281-POLY. 

Han, C. C.,"Kinetics of Polymer Phase Separation", 

Encyclopedia of Materials: Science and Technology 2000. 

Harris, G. R.; Preston, R. C., and DeReggi, A. S.,"The Impact 

of Piezoelectric PVDF on Medical Ultrasound Exposure 

Measurements, Standards and Regulations", IEEE 

Transactions on Ultrasonics, Ferroelectrics and Frequency 

Control 2000; 47(6):1321-1335. 

Hobbie, E. K.,"Depletion-Driven Phase Separation and 

Reversible Aggregation in Confined Colloidal Mixtures", 

Langmuir 1999 Dec 21; 15(26):8807-8812. 

Hobbie, E. K. and De Reggi, A. S.,"Laser-Pulse Technique for 

Measuring the Thermal Diffusivity of Substrate-Supported 

Polymer Films", Review of Scientific Instruments 1999 

Nov; 70(11):4356-4358. 
Publications

68

Hobbie, E. K. and Stewart, A. D.,"Internal Dynamics and 

Elasticity of Confined Entropic Gels", Physical Review E 

2000 May; 61(5):5540-5544. 

Holmes, G. A.; Feresenbet, E.; Pohl, E.; McDonough, W. G.; 

Raghavan, D., and Thompson, D., "Factors that Affect 

Adhesion at the Fiber-Matrix Interface in Composites", 

Proc. of the 23rd Annual Meeting of The Adhesion Society; 

Blacksburg, VA. 

Holmes, G. A.; Hunston, D. L.; McDonough, W. G., and 

Peterson, R. C., "A New Methodology for Determining 

Interfacial Shear Strength in Single Fiber Composites", 

Advanced Composite Technology for 21st Century 

Transportation . 

---, "Single Fiber Composites: A New Methodology for 

Determining Interfacial Shear Strength", Proc. of the 2000 

Annual Technical Conf. of the Society of Plastics 

Engineers. 

---, "A Test Method for Assessing Interfacial Shear Strength in 

Composites", Proc. of SAMPE 2000 Meeting. 

Holmes, G. A.; Petersen, R. C.; Hunston, D. L.; McDonough, 

W. G., and Schutte, C. L., " The Effect of Non-Linear 

Viscoelasticity on Interfacial Shear Strength 

Measurements", in Time Dependent and Nonlinear Effects 

in Polymers and Composites, ed.: West Conshohocken: 

ASTM; 2000; pp. 98-117 . 

Holmes, G. A.; Peterson, R. C.; Hunston, D. L., and 

Mcdonough, W. G.,"E-Glass/Dgeba/M-Pda Single Fiber 

Composites: the Effect of Strain Rate on Interfacial Shear 

Strength Measurements", Polymer Composites 2000 Jun; 

21(3):450-465. 

Hunston, D.; Holmes, G., and Peterson, R.,"Viscoelastic 

Properties of a Resin Commonly Used in the Single Fiber 

Fragmentation Test", Journal of Reinforced Plastics and 

Composites 1999; 18(18):1346-1657. 

Hunston, D. L.; He, J.; Raghavan, R., and Hoffman, D., "Load 

History Dependence of Fracture in Rubber-Toughened 

Epoxies", Proc. of the 23rd Annual Meeting of The 

Adhesion Society Meeting.; Blacksburg, VA. 

Hunston, D. L.; Holmes, G. A.; Peterson, R. C., and 

Mcdonough, W. G.,"Strain Rate Effects in the Single Fiber 

Fragmentation Test for Fiber-Matrix Adhesion", Abstracts 

of Papers of the American Chemical Society 1999 Aug 22; 

218:251-PMSE. 

Jeon, H. S. and Nakatani, A. I.,"Shear-Induced Novel 

Structure in Phase-Separated Polybutadiene/Polyisoprene 

Blends", Abstracts of Papers of the American Chemical 

Society 2000 Mar 26; 219:159-PMSE. 

Jeon, H. S.; Nakatani, A. I.; Han, C. C., and Colby, R. 

H.,"Effects of Domain Interfaces on the Rheological 

Properties of Polybutadiene/Polyisoprene Blends", 

Abstracts of Papers of the American Chemical Society 

2000 Mar 26; 219:6-PMSE. 

Jeon, H. S.; Nakatani, A. I.; Hobbie, E. K., and Han, C. 

C.,"Phase Inversion of Polybutadiene/Polyisoprene Blends 

Under Quiescent and Shear Conditions", Langmuir 2000. 

Karim, A. and Douglas, J. F.,"Polymer-Surface Interactions in 

Nanofilled Polymers", Abstracts of Papers of the American 

Chemical Society 2000 Mar 26; 219:73-PMSE. 

Karim, A.; Douglas, J. F.; Nisato, G.; Liu, D. W., and Amis, 

E. J.,"Transient Target Patterns in Phase Separating Filled 

Polymer Blends", Macromolecules 1999 Sep 7; 

32(18):5917-5924. 

Karim, A.; Liu, D. W.; Douglas, J. F.; Nakatani, A. I., and 

Amis, E. J.,"Modification of the Phase Stability of 

Polymer Blends by Fillers", Polymer 2000 Nov; 

41(23):8455-8458. 

Karim, A.; Sehgal, A., and Amis, E. J., "AFM Studies of 

Confined Dewetting on Gradient Patterned Surfaces", 

Abstract for 2000 ACS Meeting; Washington, DC. 

Kelly, J. R.; Berninghaus, M. E., and Antonucci, J. 

M.,"Failure Behavior and Modeling of All-Ceramic Fpd 

Connectors", Journal of Dental Research 2000; 79:165. 

Khatri, C. A.; Antonucci, J. M., and Stansbury, J. 

W.,"Synthesis and Characterization of Urethane 

Derivatives of Bis- GMA", Journal of Dental Research 

2000; 79:29. 
Publications

69

Khatri, C. A.; Antonucci, J. M.; Stansbury, J. W., and 

Schultheisz, C. R.,"Synthesis, Characterization and 

Evaluation of Urethane Derivatives of Bis-GMA", 

Polymer Preprints ACS National Meeting, Washington, 

D.C. 2000. 

Kielhorn, L.; Colby, R. H., and Han, C. C.,"Relaxation 

Behavior of Polymer Blends After the Cessation of Shear", 

Macromolecules 2000 Apr 4; 33(7):2486-2496. 

Kim, G.; Jackson, C. L.; Prosa, T. J.; Liu, D.-W., and Bauer, 

B. J.,"Nanocomposites of Molecularly Dispersed 

Polyamidoamine (PAMAM) Dendrimers", ACS-PMSE 

Preprints 2000; 82:296. 

Kim, S. D.; Klein, A.; Sperling, L. H.; Boczar, E. M., and 

Bauer, B. J.,"SANS Study of Sulfite End Group Effect on 

Polystyrene Self-Diffusion", Macromolecules 2000 Oct 

31; 33(22):8334-8343. 

Kofinas, P.; Drzal, P. L., and Barnes, J. D.,"Path Dependent 

Microstructure Orientation During Plane Strain 

Compression of Semicrystalline Block Copolymers", 

Polymer in press. 

Kolb, R.; Nakatani, A. I.; Barnes, K. A.; Barnes, J. D., and 

Hammouda, B.,"Microstructure Analysis Using 

Temperature Induced Contrast Variation in Small-Angle 

Scattering", Journal of Applied Crystallography 2000; 

33:758-762. 

Kueh, S.; Parnas, R. S.; Dunkers, J. P.; Advanti, S. G.; 

Furrows, P. S.; Jones, M. E., and Bailey, T. A., "Long 

Period Gratings as Flow Sensors for Liquid Composite 

Molding", Proc. of the SPIE’s 5th Intl. Symposium on 

Nondestructive and Health Monitoring of Aging 

Infrastructure. 

Kueh, S. R. M.; Advani, S. G., and Parnas, R. S.,"Sensor 

Placement Study for Online Flow Monitoring in Liquid 

Composite Molding", Polymer Composites 2000 Jun; 

21(3):436-449. 

La Nave, E.; Scala, A.; Starr, F. W.; Sciortino, F., and Stanley, 

H. E.,"Instantaneous Normal Mode Analysis of 

Supercooled Water", Physical Review Letters 2000 May 

15; 84(20):4605-4608. 

Lee, B. P.; Douglas, J. F., and Glotzer, S. C.,"Filler-Induced 

Composition Waves in Phase-Separating Polymer Blends", 

Physical Review E 1999 Nov; 60(5):5812-5822. 

Lee, H. J.; Lin, E. K.; Lan, J. K.; Cheng, Y. L.; Liou, H. C.; 

Wu, W. L.; Wang, Y. L.; Feng, M. S., and Chao, C. 

G.,"Investigation of N2 Plasma Effects on the Depth 

Profile of Hydrogen Silsesquioxane Thin Films Using 

High Resolution Specular X-Ray Reflectivity", Proc. of 

the 2000 Intl. Conf. on Characterization and Metrology for 

ULSI Technology 2000. 

Lenhart, J. L.; Van Zanten, J. H.; Dunkers, J. P., and Parnas, 

R. S.,"Interfacial Response of a Fluorescent Dye Grafted 

to Glass", Langmuir 2000 Oct 17; 16(21):8145-8152. 

Lenhart, J. L.; Van Zanten, J. H.; Dunkers, J. P.; Zimba, C. G.; 

James, C. A.; Pollack, S. K., and Parnas, R. 

S.,"Immobilizing a Fluorescent Dye Offers Potential to 

Investigate the Glass/Resin Interface", Journal of Colloid 

and Interface Science 2000 Jan 1; 221(1):75-86. 

Lenhart, J. L.; vanZanten, J. H.; Dunkers, J., and Parnas, R., 

"A Practical Fiber Optic Sensor to Monitor Resin Cure and 

Interphase Formation", ANTEC 2000 Proceedings; 

Orlando, FL. 

Liao, K.; Schultheisz, C. R., and Hunston, D. L.,"Effects of 

Environmental Aging on the Properties of Pultruded 

GFRP", Composites Part B-Engineering 1999; 30(5):485-

493.

Lin, E. K.; Lee, H. J.; Wang, H., and Wu, W. L.,"Structure 

and Property Characterization of Low-k Dielectric Porous 

Thin Films Determined by X-ray Reflectivity and SmallAngle Neutron Scattering", Proc. of the 2000 Intl. Conf. on 

Characterization and Metrology for ULSI Technology 

2000.

Lin, E. K.; Pochan, D. J.; Wu, W. L., and Satija, S. K., 

"Neutron reflectivity Measurements of Molecular Mass 

Effects on Polymer Mobility near the Polymer/Solid 

Interface", Proc. of the Materials Research Society Mtg. 

Lin, E. K.; Wu, W. L.; Jin, C., and Wetzel, J. T., "Structure 

and Property Characterization of Porous Low-k Dielectric 

Constant Thin Films using X-ray Reflectivity and Smallangle Neutron Scattering", Proc. of the Materials Research 

Society Meeting. 
Publications

70

Lovell, L. G.; Lu, H.; Stansbury, J. W., and Bowman, C. 

N.,"The Effect of Cure Rate on the Mechanical Properties 

of Dental Resins", Journal of Dental Research 2000; 79:33. 

Majumdar, B. S. and Hunston, D. L., " Continuous Parallel 

Fiber Composites: Fracture", in Encyclopedia of 

Materials: Science and Technology, ed.: Oxford, England: 

Pergamon Press; in press. 

Martys, N. S. and Douglas, J. F.,"Critical Properties and Phase 

Separation in Lattice Boltzmann Fluid Mixtures", Physical 

Review E 2000 May. 

McBrearty, M.; Bur, A. J., and Roth, S. C., "Real-Time 

Dielectric Measurements During Extrusion of Filled 

Polymers", Proc. of Annual Technical Meeting of the 

Society of Plastics Engineers ; Orlando, FL. 

McDonough, W. G.; Antonucci, J. M., and Dunkers, J. 

P.,"Interfacial Shear Strengths of Dental Composites by 

the Microbond Test", Dental Composites in press. 

Mcdonough, W. G.; Antonucci, J. M.; Schumacher, G. E.; 

Shimada, Y.; Chiang, M.; He, J., and Dunkers, J. 

P.,"Improvements of a Micro Shear Test for the Study of 

Adhesion", Journal of Dental Research 2000; 79:28. 

McDonough, W. G.; Dunkers, J. P.; Holmes, G. A., and 

Parnas, R. P., "The Effect of Processing on Interfacial 

Shear Properties of Composite Materials", Proc. of the 

23rd Annual Meeting of The Adhesion Society. 

Meredith, J. C. and Amis, E. J.,"Lcst Phase Separation in 

Biodegradable Polymer Blends: Poly(D,L-Lactide) and 

Poly(Epsilon-Caprolactone)", Macromolecular Chemistry 

and Physics 2000 Apr 14; 201(6):733-739. 

Meredith, J. C.; Karim, A., and Amis, E. J.,"High-Throughput 

Measurement of Polymer Blend Phase Behavior", 

Macromolecules 2000 Aug 8; 33(16):5760-5762. 

Migler, K. B.,"Droplet Vorticity Alignment in Model Polymer 

Blends", Journal of Rheology 2000 Mar-2000 Apr 30; 

44(2):277-290. 

---,"Wall-Induced String Formation in Sheared Polymer 

Blends", Physical Review Letters in press. 

Migler, K. B.; Hobbie, E. K., and Qiao, F.,"In Line Study of 

Droplet Deformation in Polymer Blends in Channel Flow", 

Polymer Engineering and Science 1999 Nov; 39(11):2282-

2291.

Migler, K. B.; Lavallée, C.; Dillon, M. P.; Woods, S. S., and 

Gettinger, C. L.,"Visualizing the elimination of sharkskin 

through fluoropolymer additives: Coating and polymerpolymer slippage", Journal of Rheology in press. 

Misra, D. N.,"Interaction of Citric or Hydrochloric Acid With 

Calcium Fluorapatite: Precipitation of Calcium Fluoride", 

Journal of Colloid and Interface Science 1999 Dec 15; 

220(2):387-391. 

Mopsik, F. I.,"Extended Frequency Range Dielectric 

Measurements of Thin Films", Review of Scientific 

Instruments 2000 Jun; 71(6):2456-2460. 

Morgan, A. B.; Antonucci, J. M.; VanLandingham, M.; Harris, 

R. H., and Kashiwagi, T.,"Thermal and Flammability 

Properties of a Silica-PMMA Nanocomposite", 

Proceedings of the ACS Division of Polymeric Materials 

Science and Engineering 2000 Aug; 83:57-58. 

Morgan, A. B.; Gilman, J. W.; Harris, R. H.; Jackson, C. L.; 

Wilkie, C. A., and Zhu, J.,"Flammability of Polystyreneclay Nanocomposites", ACS PMSE Preprints 2000; 83:53. 

Morgan, A. B.; Gilman, J. W., and Jackson, C. 

L.,"Characterization of Polymer-Clay Nanocomposites: 

XRD vs. TEM", ACS PMSE Preprints 2000; 82: 270. 

Morgan, A. B.; Gilman, J. W.; Kashiwagi, T., and Jackson, C. 

L., "Flammability of Polymer-Clay Nanocomposites", 

Flame Retardant Chemicals Association Meeting 

Proceedings. 

Morgan, A. B; Gilman, J. W.; Nyden, M., and Jackson, C. L., 

" New Approaches to the Development of Fire-Safe 

Materials", NISTIR 6465; 2000 Feb. 

Nakatani, A. I., " Phase Separation Kinetics During Shear in 

Compatibilized Polymer Blends", in Scattering From 

Polymers, ed.: 2000; pp. 405-434. 

Nakatani, A. I.; Chen, W.; Schmidt, R. G., and Han, C. 

C.,"Chain Dimensions in Polysilicate-Filled 

Poly(Dimethyl Siloxane)", Polymer in press. 
Publications

71

Nakatani, A. I.; Ivkov, R.; Papanek, P.; Yang, H., and 

Gerspacher, M.,"Concentration Dependence of Bound 

Polymer Dynamics by Inelastic Neutron Scattering", ACS 

PMSE Preprint. 2000. 

---,"Inelastic Neutron Scattering from Filled Elastomers", 

Rubber Chemistry and Technology in press. 

Nisato, G.; Ivkov, R., and Amis, E. J.,"Size Invariance of 

Polyelectrolyte Dendrimers", Macromolecules 2000 May 

30; 33(11):4172-4176. 

---,"Structure of Charged Dendrimer Solutions as Seen by 

Small-Angle Neutron Scattering", Macromolecules 1999 

Sep 7; 32(18):5895-5900. 

Nozaki, R. and Obrzut, J., "Permittivity Measurements of 

Solid Film Dielectrics at Microwave Frequencies", IPC 

EXPO-00 Technical Conference. 

Nyden, M. R.; VanderHart, D. L., and Alamo, R. G.,"The 

Conformational Structures of Defect-Containing Chains in 

the Crystalline Regions of Isotactic Polypropylene", 

Computational and Theoretical Polymer Science. in press. 

Obrzut, J. and Chaing, C. K., "Microwave Dielectric 

Characterization of Polyaniline Composites ", 

Organic/Inorganic Hybrid Materials. 

Obrzut, J. and Chiang, C. K., " Dielectric Measurements of 

Embedded Capacitance Materials", Embedded 

Capacitance Project Report2000 Aug. 

Obrzut, J.; Chiang, C. K.; Popielarz, R., and Nozaki, 

R.,"Evaluation of Dielectric Properties of Polymer ThinFilms Materials for Application in Embedded 

Capacitance", NISTIR 6537 2000. 

Okuno, O.; Asaoka, K., and Tesk, J. A., " High-Temperature 

Investments", in Dental Materials and their selection, ed.: 

2000.

Park, J. Y. and Mckenna, G. B.,"Size and Confinement Effects 

on the Glass Transition Behavior of Polystyrene/OTerphenyl Polymer Solutions", Physical Review B 2000 

Mar 1; 61(10):6667-6676. 

Park, M. S.; Eanes, E. D.; Antonucci, J. M., and Skrtic, 

D.,"Mechanical Properties of Bioactive Amorphous 

Calcium Phosphate/Methacrylate Composites", Dental 

Materials 1998 Mar; 14(2):137-141. 

Parnas, R. S. and Flynn, K. M., " Recommended Practice 

Guide for Measuring and Interpreting Permeability", 

NISTIR 6542; 2000. 

Pillai, K. M.; Tucker, C. L., and Phelan, F. R.,"Numerical 

Simulation of Injection/Compression Liquid Composite 

Molding. Part 1. Mesh Generation", Composites Part aApplied Science and Manufacturing 2000; 31(1):87-94. 

Pochan, D. J.; Lin, E. K., and Wu, W. L.,"Surface Directed 

Crystallization and Autophobic in Semicrystalline Polymer 

Thin Films", Macromolecules 2000. 

Popielarz, R.; Chiang, C. K.; Nozaki, R., and Obrzut, J., 

"Preparation and Characterization of Photopatternable 

BaTiO3/Polymer Composites", Organic/Inorganic Hybrid 

Materials; San Francisco, CA. 

Pursch, M.; Vanderhart, D. L.; Sander, L. C.; Gu, X. H.; 

Nguyen, T.; Wise, S. A., and Gajewski, D. A.,"C-30 SelfAssembled Monolayers on Silica, Titania, and Zirconia: 

HPLC Performance, Atomic Force Microscopy, 

Ellipsometry, and NMR Studies of Molecular Dynamics 

and Uniformity of Coverage", Journal of the American 

Chemical Society 2000 Jul 26; 122(29):6997-7011. 

Qiao, F.; Migler, K. B., and Han, C. C.,"Stability of Blends of 

Polyether Sulfone with Thermotropic Liquid Crystalline 

Polymers", Proc. of the ANTEC 2000 Meeting 2000. 

Qiao, F.; Migler, K. B.; Hunston, D. L., and Han, C. 

C.,"Reactive Compatibilization and In-line Morphological 

Analysis of Blends of PET and a Thermotropic Liquid 

Crystalline Polymer", Polymer Engineering and Science in 

press. 

Sambasvian, S. Fischer D. A. Shen M. C. Tesk J. A. Hsu S. 

M., "Effects of Annealing on UHMWPE Annealing", 

Transactions of 6th World Biomaterials Congress; 

Kameuela, HA. 

Sastry, S.; Debenedetti, P. G.; Stillinger, F. H.; Schroder, T. 

B.; Dyre, J. C., and Glotzer, S. C.,"Potential Energy 

Landscape Signatures of Slow Dynamics in Glass Forming 

Liquids", Physica a 1999 Aug 1; 270(1-2):301-308. 
Publications

72

Scala, A.; Starr, F. W.; La Nave, E.; Sciortino, F., and Stanley, 

H. E.,"Configurational Entropy and Diffusivity of 

Supercooled Water", Nature 2000 Jul 13; 406(6792):166-

169.

Schmidt, G.; Nakatani, A. I.; Butler, P. D.; Karim, A., and 

Han, C. C., "Shear Orientation of a Viscoelastic PolymerClay Solution", Proc. of the XIIIth Intl. Congress of 

Rheology; Cambridge, UK. 

---,"Shear Orientation of Viscoelastic Polymer-Clay Solutions 

Probed by Flow Birefringence and Sans", Macromolecules 

2000 Oct 3; 33(20):7219-7222. 

Schreyer, A.; Majkrzak, C. F.; Berk, N. F.; Grull, H., and Han, 

C. C.,"Using Polarized Neutrons to Determine the Phase of 

Reflection From Thin Film Structures", Journal of Physics 

and Chemistry of Solids 1999 Aug-1999 Sep 30; 60(8-

9):1045-1051. 

Schultheisz, C. R. and McKenna, G. B., "Simultaneous 

Measurement of Torque, Axial Normal Force and Volume 

Change in the NIST Torsional Dilatometer - Experiments 

and Analysis", Proc. of the Society of Plastics Engineers 

Annual Technical Conference 2000.

---, "Standard Reference Materials: Non-Newtonian Fluids for 

Rheological Measurements", Proc. of the Society of 

Plastics Engineers Annual Technical Conference 2000.

Shen, M. C. Hsu S. M. Tesk J. A. and Christou A., "Wear 

Analysis of UHMWPE Using a Load Sum Method", 

Transactions of 6th World Biomaterials Congress; 

Kameuela, HA. 

Shimada, Y.; Antonucci, J. M.; Schumacher, G. E.; 

Mcdonough, W. G., and Tagami, J.,"Micro-Shear Bond 

Strength of Resin Bonding Systems to Enamel Surfaces", 

Journal of Dental Research 2000; 79:3629. 

Simon, Jr. C. G.; Holloway, P. W., and Gear, A. R. 

L.,"Exchange of C16-Ceramide Between Phospholipid 

Vesicles", Biochemistry 1999 Nov 2; 38(44):14676-14682. 

Skrtic, D.; Antonucci, J. M., and Eanes, E. D.,"Effect of the 

Monomer and Filler Systems on the Remineralizing 

Potential of Bioactive Dental Composites Based on 

Amorphous Calcium Phosphate", Polymers for Advanced 

Technologies 2000 Jun 1. 

Skrtic, D.; Antonucci, J. M.; Eanes, E. D.; Eichmiller, F. C., 

and Schumacher, G. E.,"Physicochemical Evaluation of 

Bioactive Polymeric Composites Based on Hybrid 

Amorphous Calcium Phosphates", Journal of Biomedical 

Materials Research 2000 Aug; 53(4):381-391. 

Skrtic, D.; Antonucci, J. M.; Eichmiller, F. C., and Stansbury, 

J. W.,"Polymerization Shrinkage and Methacrylate 

Conversion in Amorphous Calcium Phosphate 

Composites", Journal of Dental Research 2000; 79:1781. 

Smith, A. P.; Carson, J. C.; Amis, E. J., and Karim, 

A.,"Morphological Characterization of Symmetric 

Copolymers Via Novel Combinatorial Methods", Abs. of 

2000 ACS Natl. Mtg., Washington, DC, August, 2000

2000.

Snyder, C. R., "High Sensitivity Technique for Measurement 

of Thin Film Out-of-Plane Expansion. II. Conducting and 

Semiconducting Samples", Proc. of the 2000 International 

Conf. on Characterization and Metrology for ULSI 

Technology. 

Snyder, C. R. and Douglas, J. F.,"Determination of the 

Dielectric Constant of Nanoparticles. I. Dielectric 

Measurements of Buckminsterfullerene Solutions", 

Journal of Physical Chemistry, Part B. 2000 Nov; 

104(47):11058-11065. 

Snyder, C. R.; Mopsik, F. I.; Marand, H.; Alizadeh, A., and 

Sohn, S. M.,"Time-Domain Dielectric Spectroscopy 

Analysis of the Amorphous Phase in Semicrystalline 

Polycarbonate", Abstracts of Papers of the American 

Chemical Society 1999 Aug 22; 218:139-PMSE. 

Soles, C. L.; Lin, E. K.; Wu, W.-L.; Zhang, C., and Laine, R. 

L., "Structural Evolution of Silsesquioxane-based 

Organic/Inorganic Nanocomposite Networks", Proc. of the 

Materials Research Society Annual Meeting. 

Stansbury, J. W.; Tanaka, J., and Antonucci, J. 

M.,"Photopolymerization Studies and Polymer Properties 

of Methacrylate/Vinyl Ester Resins", Journal of Dental 

Research 2000; 79:2896. 

Starr, F. W.; Nielsen, J. K., and Stanley, H. E.,"HydrogenBond Dynamics for the Extended Simple Point-Charge 

Model of Water", Physical Review E 2000 Jul; 62(1):579-

587.
Publications

73

Starr, F. W.; Sciortino, F., and Stanley, H. E.,"Dynamics of 

Simulated Water Under Pressure", Physical Review E 

1999 Dec; 60(6):6757-6768. 

Tanaka, J.; Stansbury, J. W., and Antonucci, J. M.,"New 

Hydrophobic Diluent Monomers for Udma and/or BisGma", Journal of Dental Research 2000; 79:1788. 

Tesk, J. A.,"NIST Reference Material for UHMWPE", 

Biomaterials Forum 2000; Nov-Dec:12. 

---,"NIST - SFB Workshop Identifies Needs for Reference 

Data and Reference Materials", Biomaterials Forum 2000; 

Nov-Dec:11. 

Thomas, C. L. and Bur, A. J.,"In-Situ Monitoring of Product 

Shrinkage During Injection Molding Using an Optical 

Sensor", Polymer Engineering and Science 1999 Sep; 

39(9):1619-1627. 

Topp A; Bauer BJ; Klimash JW; Spindler R; Tomalia DA, and 

Amis EJ,"Probing the location of the terminal groups of 

dendrimers in dilute solution", Macromolecules 1999 Oct 

19; 32(21):7226-7231. 

Topp A; Bauer BJ; Prosa TJ; Scherrenberg R, and Amis, 

EJ,"Size change of dendrimers in concentrated solution", 

Macromolecules 1999 Dec 28; 32(26):8923-8931. 

Topp A; Bauer BJ; Tomalia DA, and Amis EJ,"Effect of 

solvent quality on the molecular dimensions of PAMAM 

dendrimers", Macromolecules 1999 Oct 19; 32(21):7232-

7237.

Vanderhart, D. L.; Alamo, R. G.; Nyden, M. R.; Kim, M. H., 

and Mandelkern, L.,"Observation-of Resonances 

Associated With Stereo and Regio Defects in the 

Crystalline Regions of Isotactic Polypropylene: Toward a 

Determination of Morphological Partitioning", 

Macromolecules 2000 Aug 8; 33(16):6078-6093. 

Vanderhart, D. L.; Feng, Y.; Han, C. C., and Weiss, R. 

A.,"Morphological Characterization of Blends of MetalSulfonated Poly(Styrene) and a Methylated Poly(Amide) 

by Solid State Nmr", Macromolecules 2000 Mar 21; 

33(6):2206-2227. 

VanderHart, D. L.; Nyden, M. R., and Alamo, R. G. and 

Mandelkern L.,"Incorporation of Stereo, Regio and 

Comonomer Defects into the Crystalline Regions of 

Isotactic Polypropylene: Results from NMR, Molecular 

Dynamics and Chemical Shift Calculations", Preprint of 

the American Chemical Society National Meeting in San 

Francisco, March, 2000. 2000. 

VanderHart, D. L.; Schen, M. A., and Davis, G. 

T.,"Partitioning of Water between Voids and the Polymer 

Matrix in a Molding Compound by Proton NMR", 

International Journal of Microcircuits and Electronic 

Packaging 1999; 22:424-439. 

Viers BD; Bauer BJ; Akpalu Y; Grohn F; Liu D-W, and Kim 

G ,"Hydrogels formed by end-linking PEG to dendrimer 

cross-link agents", ACS Polymer Preprints 2000; 

41(1):728-729. 

Von Gonten, A. S.; Kelly, J. R., and Antonucci, J. M.,"LoadBearing Behavior of a Simulated Craniofacial Structure 

Fabricated From a Hydroxyapatite Cement and 

Bioresorbable Fiber-Mesh", Journal of Materials ScienceMaterials in Medicine 1999; 11(2):95-100. 

Wallace, W. E.; Guttman, C. M., and Antonucci, J. M.,"MaldiTof Mass Spectrometry of Polymeric Silsesquioxanes", 

Abstracts of Papers of the American Chemical Society 

2000 Mar 26; 219:20-POLY. 

---,"Polymeric Silsesquioxanes: Degree-of-IntramolecularCondensation Measured by Mass Spectrometry", Polymer 

2000 Mar; 41(6):2219-2226. 

Wu, W.; Lin, E. K.; Jin, C., and Wetzel, J. T., "A Three-Phase 

Model for the Structure of Porous Thin Films Determined 

by X-ray Reflectivity and Small Angle Neutron 

Scattering", Proc. of the Materials Research Society 

Meeting; San Francisco, CA. 

Wu, W. L.; Lin, E. K.; Lin, Q., and Angelopolous, M., "SmallAngle Neutron Scattering Measurements for the 

Characterization of Lithographically Prepared Structures", 

Proc. of the 2000 Intl. Conf. on Characterization and 

Metrology for ULSI Technology. 

Wu, W.-L.; Lin, E. K.; Lin, Q., and Angelopolous, M.,"Small 

Angle Neutron Scattering Measurements of Nanoscale 

Lithographic Features", J. Appl. Phys. 2000; 88(12). 
Publications

74

Wu, W. L.; Wallace, W. E.; Lin, E. K.; Lynn, G. W.; Glinka, 

C. J.; Ryan, E. T., and Ho, H. M.,"Properties of 

Nanoporous Silica Thin Films Determined by HighResolution X-Ray Reflectivity and Small-Angle Neutron 

Scattering", Journal of Applied Physics 2000 Feb 1; 

87(3):1193-1200. 

Xu, H. H. K.; Eichmiller, F. C.; Antonucci, J. M., and Flaim, 

G. M.,"Single-Crystalline Ceramic Whisker-Reinforced 

Carboxylic Acid- Resin Composites With Fluoride 

Release", Operative Dentistry 2000 Mar-2000 Apr 30; 

25(2):90-97. 

Xu, H. H. K.; Eichmiller, F. C.; Antonucci, J. M.; 

Schumacher, G. E., and Ives, L. K.,"Dental Resin 

Composites Containing Ceramic Whiskers and Precured 

Glass Ionomer Particles", Dental Materials 2000 Sep; 

16(5):356-363. 

Xu, H. H. K.; Giuseppetti, A. A.; Eichmiller, F. C.; Antonucci, 

J. M.; Schumacher, G. E., and Flaim, G. M.,"Composites 

Containing Ceramic Whiskers and Precured Glass Ionomer 

Particles", Journal of Dental Research 2000; 79:1787. 

Xu, H. H. K.; Smith, D. T.; Schumacher, G.; Eichmiller, F. C., 

and Antonucci, J. M.,"Indentation Modulus and Hardness 

of Whisker-Reinforced Heat- Cured Dental Resin 

Composites", Dental Materials 2000 Jul; 16(4):248-254. 

Xu, H. H. K.; Smith, D. T.; Schumacher, G. E.; Eichmiller, F. 

C.; Antonucci, J. M., and Stansbury, J. W.,"WhiskerReinforced Composites: Effects of Filler Level, Heat- Cure 

Temperature and Time", Journal of Dental Research 2000; 

79:3640. 

Zhang, K. J.; Briggs, M. E.; Gammon, R. W.; Sengers, J. V., 

and Douglas, J. F.,"Thermal and Mass Diffusion in a 

Semidilute Good Solvent-Polymer Solution", Journal of 

Chemical Physics 1999 Aug 1; 111(5):2270-2282. 

Zhang, Y.; Douglas, J. F.; Ermi, B. D., and Amis, E. 

J.,"Influence of Counterion Valency on the Scattering 

Properties of Highly Charged Polyelectrolyte Solutions", 

J. of Chemical Physics in press. 
75
Staff

76

Polymers Division 

Chief 

Eric J. Amis 

Phone: 301-975-6762 

E-mail: eric.amis@nist.gov 

Deputy Chief 

Bruno M. Fanconi 

Phone: 301-975-6769 

E-mail: bruno.fanconi@nist.gov 

NIST Fellow 

Charles C. Han 

Phone: 301-975-6772 

E-mail: charles.han@nist.gov 

Group Leaders 

Electronics Materials 

Wen-Li Wu 

Phone: 301-975-6839 

E-mail: wen-li.wu@nist.gov 

Biomaterials 

Francis W. Wang 

Phone: 301-975-6726 

E-mail: francis.wang@nist.gov 

Multiphase Materials 

Charles Han 

 Multivariant Measurement Methods 

Alamgir Karim 

Phone: 301-975-6588 

E-mail: alamgir.karim@nist.gov 

Characterization and Measurement 

Method Development 

Wen-li Wu 

 Standards and Data 

Bruno Fanconi 

Internal Capabilities 

Eric J. Amis, Acting 

Processing Characterization 

Kalman Migler 

Phone: 301-975-4876 

E-mail: kalman.migler@nist.gov 
Staff

77

Research Staff

Akpalu, Yvonne+

yvonne.akpalu@nist.gov 

 Crystallization, structure and morphology of polymers 

 Small angle and wide angle x-ray scattering 

Thin film phase behavior of polymer blends 

Amis, Eric J. 

eric.amis@nist.gov 

Neutron, x-ray and light scattering 

Polyelectrolytes 

Viscoelastic behavior of polymers 

Dendrimers and dendritic polymers 

Functional Biomaterials 

Antonucci, Joseph M. 

joseph.antonucci@nist.gov 

Synthetic and polymer chemistry 

Dental composites, cements and adhesion 

Initiator systems 

Interfacial coupling agents 

Remineralizing polymer systems 

Ashley, Karen+

karenmashley@hotmail.com 

Polymer Thin Films 

Dewetting 

Combinatorial Measurements 

Balizer, Edward+

Neutron, x-ray scattering 

Polymer electrostriction 

Barnes, John D. 

john.barnes@nist.gov 

Gas and vapor transport in polymers 

X-ray scattering 

Computer applications in polymer measurements 

Barnes, Kathleen A.+

kathleen.barnes@nist.gov 

Polymer blends, polymer/filler interactions 

Thin film phase behavior 

Neutron scattering, AFM, optical microscopy and 

Rheology 

Bauer, Barry J. 

barry.bauer@nist.gov 

Polymer synthesis Thermal characterization 

Neutron, x-ray and light scattering 

Dendrimers, metallic ions nanocluster 

Beers, Kathryn 

kathryn.beers@nist.gov 

Crystallization in thin films 

Optical light scattering 

Controlled/living polymerizations 

Blair, William R. 

william.blair@nist.gov 

Polymer analysis by size exclusion 

ChromatographyDiffusion and absorption of gases in 

Polymeric matrices 

Mass spectrometry of polymers 

Bowen, Rafael L.* 

rafael.bowen@nist.gov 

Adhesion 

Dental composites 

Novel Monomer Synthesis 

Bur, Anthony J. 

Anthony.bur@nist.gov 

Dielectric properties of polymers

Fluorescence and optical monitoring of polymer 

processing 

Piezoelectric, pyroelectric polymers 

Viscoelastic properties of polymers 

Cantoni, Giovana+

giovanna.cantoni@nist.gov 

Biomaterials and biopolymers 

Polymer thin films 

Tissue engineering 
Staff

78

Carey, Clifton M.* 

clifton.carey@nist.gov 

Dental plaque 

Microanalytical analysis techniques 

Phosphate chemistry 

Ion-selective electrodes 

Chang, Shu Sing+

Thermal properties of polymeric and composite 

materials 

Composite process monitoring 

Electronic packaging materials 

Polymer phase transitions 

Precision electrical and temperature measurements 

Chen, Erqiang+

erqiang_chen@hotmail.com

Polymer morphology 

Phase behavior of block copolymers 

Polymer blends 

Chen, Wei+

wchen2.email.com@dcrn.e-mail.com

X-ray and neutron scattering 

Low dielectric constant material characterization 

Cherng, Maria* 

maria.cherng@nist.gov 

Calcium phosphate biomaterials 

Chiang, Chwan K. 

c.chiang@nist.gov 

Electroluminescent polymers 

Residual stress 

Impedance spectroscopy 

Chiang, Martin Y. 

martin.chiang@nist.gov 

Computational mechanics (finite element analysis) 

Strength of materials, Fracture Mechanics 

Engineering mechanics of polymer based materials 

Bi-material interface 

Chow, Laurence C.* 

laurence.chow@nist.gov 

Calcium phosphate compounds and biomaterials 

Dental and biomedical cements 

Solution chemistry 

Topical dental fluorides 

Crosby, Alfred 

alfred.crosby@nist.gov 

Polymer Adhesion 

Polymer Fracture 

Viscoelasticity 

Elastomers 

Block copolymers 

 Dähnhardt, Jan-Erik+

Self-curing dental repair resin 

Davis, G. Thomas+

george.davis@nist.gov 

Electronic packaging 

Polymer crystallization 

X-ray diffraction of polymers 

Polarization distribution 

Piezoelectricity in polymers 

DeReggi, Aime S 

aime.dereggi@nist.gov 

Polarization-depth profiles in polymers 

Space charge in dielectrics 

Ferroelectric polymers 

Polymeric piezo- & pyroelectric devices 

Dickens, Sabine* 

sabine.dickens@nist.gov 

Dental composites 

Dental adhesives 

Transmission electron microscopy 

Di Marzio, Edmund A.+

edmund.dimarzio@nist.gov 

Statistical mechanics of polymers 

Phase transitions 

Glasses 

Polymers at interfaces 

Douglas, Jack F. 

jack.douglas@nist.gov 

Theory on polymer solutions, blends, and filled 

polymers 

Transport properties of polymer solutions and 

suspensions 

Polymers at interfaces 

Scaling and renormalization group calculation 

Dunkers, Joy P. 

joy.dunkers@nist.gov 

Optical coherence tomography 

Image analysis 

Fiber optic spectroscopy 

Infrared microspectroscopy of polymers 

Eanes, Edward D.+

edward.eanes@nist.gov 

Structure of bones and teeth 

Calcium phosphate compounds as dental materials 

Effects of solution and biological molecules on 

precipitation of calcium phosphates 

Liposome studies 
Staff

79

Eichmiller, Frederick C.* 

frederick.eichmiller@nist.gov 

Clinical dentistry 

Composites 

Dentin adhesives 

Eidelman, Naomi N.* 

Naomi.eidelman@nist.gov 

Prevention of calcification in the cardiovascular 

system 

Effect of phosphonates, cholesterol and 

phospholipids on calcium phosphate formation 

Characterization of calcified deposits by FTIR 

microscopy 

Esker, Alan R.+

alan.esker@nist.gov 

Membrane mediated polymer interdiffusion 

Phase separation kinetics of polymer blends 

Fanconi, Bruno M. 

bruno.fanconi@nist.gov 

Infrared & Raman spectroscopy of polymers 

Structure of polymers 

Polymer fracture 

Process monitoring of polymer composites 

Feresenbet, Elias+

Silane deposition 

Composite interfaces 

Flaim, Glenn M.* 

glenn.flaim@nist.gov 

Fabricating dental composites 

Floyd, Cynthia J. E.+

cynthia.floyd@nist.gov 

Dental composites 

Flynn, Kathleen M. 

kathleen.flynn@nist.gov 

Permeability measurements and database 

Flow visualization experiments 

Web page development 

Fowler, Bruce O.+

bruce.fowler@nist.gov 

Infrared and Raman spectroscopy 

Structure of calcium phosphates, bones, and teeth 

Composites 

Frukhtbeyn, Stanislav+

Calcium phosphate compounds and biomaterials 

Topical dental fluorides 

Galvin, Agnes Ly.* 

agnes.galvin@nist.gov 

Clinical dental assistant 

Adhesion measurements 

George, Laurie A.* 

laurie.george@nist.gov 

Glass-ceramics 

Giuseppetti, Anthony A.* 

anthony.giuseppetti@nist.gov 

Casting of dental alloys 

Mercury-free amalgam alterative 

Glotzer, Sharon C. 

sharon.glotzer@nist.gov 

Theoretical and computational materials science 

Disordered systems and pattern formation 

Dynamics and structure in soft materials 

Liquid crystals glasses 

Groehn, Franziska+

franziska.groehn@nist.gov 

Neutron and x-ray scattering 

Electron microscopy 

Dendrimers 

Nanocomposites 

Nanocrystals 

Organic-inorganic hybrids 

Guttman, Charles M. 

charles.guttman@nist.gov 

Solution properties of polymers 

Size exclusion chromatography 

Mass spectroscopy of polymers 

Diffusion and absorption of gases by polymers 

Han, Charles C. 

charles.han@nist.gov 

Phase behavior of polymer blends 

Phase separation kinetics of polymer blends 

Polymer characterization and diffusion 

Shear mixing/demixing and morphology control 

of polymer blends 

Static, time resolved, and quasi-elastic scattering 

of light and neutron 

Jinamei He 

jianmei.he@nist.gov 

 Computational mechanics (finite element modeling) 

 Adhesive joints 

 Structural optimization 
Staff

80

Hedden, Ronald 

ronald.hedden@nist.gov 

Siloxane polymers: synthesis and properties of 

monomers, linear chains, and networks 

Mechanical properties of elastomers 

Polymer fractionation 

Gel permeation chromatography

Hirayama, Satoshi+

satoshi.hirayama@nist.gov 

Calcium phosphate cement 

Biocompatability 

Hobbie, Erik K. 

erik.hobbie@nist.gov 

Light scattering and optical microscopy 

Dynamics of complex fluids 

Shear induced structures in polymer blends and 

solutions 

Holmes, Gale A. 

gale.homes@nist.gov 

Composite interface science 

Chemical structure-mechanical property 

relationships for polymers 

Polymer chemistry 

Mass spectroscopy 

Hotta, Yasuhiro+

yasuhiro.hotta@nist.gov 

Dental CAD/CAM 

Investment for titanium casting 

Fluorescence spectroscopy 

Hunston, Donald L. 

donald.hunston@nist.gov 

Adhesion science and technology 

Fracture behavior of polymers 

Processing and failure behaviors of polymer 

composites 

Flow behavior of dilute high polymer solutions 

Macromolecular-small molecule binding 

Hybrid reinforced composites 

Hussain, Latiff* 

latiff.hussain@nist.gov 

Monomer polymer synthesis, characterization, testing 

Dental composites, adhesives 

Jackson, Catheryn L. 

catheryn.jackson@nist.gov 

Structure and morphology of polymers 

Transmission and scanning electron microscopy 

Finite-size effects on crystalline melting and glass 

transition temperatures 

Liquid crystalline polymers 

Microcellular foams morphology 

Atomic force microscopy 

Jeon, Hyun Sik+

hyunsik.jeon@nist.gov 

Shear light scattering and optical microscopy 

Structure and morphology of two-phase elastomer 

blends under shear 

Jones, Ronald+

ronald.jones@nist.gov

Neutron and x-ray scattering 

Neutron reflectivity 

Polymer surfaces and thin films 

Polymer phase transitions and computer simulation 

Karim, Alamgir 

alamgir.karim@nist.gov 

Polymer fillers and nanocomposites 

Patterning of thin polymer blend films on 

inhomogenous surfaces 

Neutron and x-ray reflection, scattering, 

AFM and optical microscopy 

Thin film phase behavior of polymer blends 

Combinatorial thin film polymer coatings 

Kelly, J. Robert+

robert.kelly@nist.gov 

Calcium phosphate cements 

Dental ceramics 

Failure analysis; dental prostheses 

Finite element analysis 

Weibull analysis 

Khatri, Chetan A.+

Chetan.khatri@nist.gov 

Monomer/polymer synthesis and characterization 

Khoury, Freddy A. 

freddy.khoury@nist.gov 

Crystallization, structure and morphology of polymers 

Analytical electron microscopy of polymers 

Wide angle and small angle x-ray diffraction 

Structure and mechanical property relationships 

Kim, Ginam+

ginam.kim@nist.gov 

Structure and morphology of polymers 

Transmission and scanning electron microscopy 

Cryo-electron microscopy 

Kryder, Samuel J.+

Electronic circuit design and construction 

Electronic troubleshooting and repair 
Staff

81

Kueh, Sylvia+

Liquid molding 

Optical fiber sensors 

Kumar, Sanat+

kumar@plmsc.psu.edu 

Polymer coatings and thin films 

Simulations 

Physical properties of polymers 

Phase Separation 

Multiphase polymer systems 

Lee, Hae-Jeong+

hae-jeong.lee@nist.gov 

X-ray reflectivity 

Small angle neutron scattering 

Synthesis and characterization of low dielectric 

constant thin films

Lenhart, Joseph L. 

joseph.lenhart@nist.gov 

Sensors 

Interphase structure 

Li, Bizhong+

Polymer processing 

Polymer blends 

Polymer-clay processing 

Liao, Nam S.* 

nam.liao@nist.gov 

Synthesis and testing of dental adhesives 

Internal stress of composition due to polymerization 

Lin, Eric K. 

eric.lin@nist.gov 

Statistical mechanics 

X-ray and neutron reflectivity 

Liu, D.-W. 

da-wei.liu@nist.gov 

Polymer synthesis 

Thermal gravimetric analysis 

Differential scanning calorimetry 

Gel permeation chromatography 

Infrared spectroscopy 

Nuclear magnetic resonance 

Scanning electron microscopy 

Atomic force microscopy 

Lynn, Gary W.+

gary.lynn@nist.gov 

X-ray and neutron reflectivity 

Optical microscopy 

Mager, Carie+

carie.mager@nist.gov 

Toughening Bioceramics 

Fracture mechanics 

Markovic, Milenko* 

milenko.markovic@nist.gov 

Calcium phosphate chemistry 

Biomineralization (normal and pathological) 

Crystal growth and dissolution kinetics 

Heterogeneous equilibria 

Mathew, Mathai* 

mathai.mathew@nist.gov 

Crystallography 

Calcium phosphate compounds 

Maurey, John M.+

john.maurey@nist.gov 

Ultracentrifugation 

Rayleigh light scattering 

Osmometry 

Densimetry 

Refractometry 

Intrinsic viscosity 

McDonough, Walter G. 

walter.mcdonough@nist.gov 

Processing and cure monitoring polymer composites 

Failure and fracture of polymers 

Polymer composite interfaces 

McKenna, Gregory B.+

greg.mckenna@coe.ttu.edu 

Failure, yield and fracture of polymers 

Nonlinear viscoelasticity 

Molecular rheology 

Physics of polymer glasses 

Rubber thermodynamics and mechanics 

Mechanics of composites 

Meredith, J. Carson 

james.meredith@nist.gov 

Biodegradable polymer blends 

Phase-separation and wetting properties of thin films 

Combinatorial methods for coatings 

Migler, Kalman 

kalman.migler@nist.gov 

Effects of shear and pressure on phase behavior 

Fluorescence and optical monitoring of polymer 

processing 

Liquid crystals 

Shear induced two phase structures 

Polymer slippage 
Staff

82

Mopsik, Frederick I.+

frederick.mopsik@nist.gov 

Dielectric measurements and behavior 

Automated measurement design 

Computerized data analysis and programming 

Electrical properties of polymers 

Mueller, Herbert J. * 

herb.mueller@nist.gov 

Dental Biomaterials 

Interfacial interactions via electrochemical and 

infrared spectroscopy 

Chevron notch fracture toughness 

Mechanical properties via nondestructive methods 

Nakatani, Alan I. 

alan.nakatani@nist.gov 

Polymer blends and solution properties under shear 

 Small angle neutron scattering 

Phase behavior of polymer blends 

Filled polymers 

Rheo-optical behavior of polymers 

Noda, Natsuko+

noda@nist.gov

Impendence spectroscopy 

Dielectric characterization of composites 

Nozaki, Ryusuke+

nozaki@charco.sci.hokudai.ac.jp

Dielectric relaxation in polymers 

Impedence spectroscopy 

Obrzut, Jan 

jan.obrzut@nist.gov 

Electronic properties of polymers and composites 

Photoelectron spectroscopy (X-ray and UV) 

Dielectric relaxation spectroscopy 

Electronic packaging 

Reliability, stress testing 

Microwave and optical waveguides 

Parnas, Richard S. 

richard.parnas@nist.gov 

Flow through porous media with heterogeneous 

structure 

Surface rheology 

Polymer dynamics 

Evancescent wave optical fiber fluorescence 

monitoring 

Control of the liquid molding process 

Parry, Edward E.* 

edward.parry@nist.gov 

Dental appliance and crown and bridges fabrication 

Machine shop applications 

Pfeiffer, Carmen+

carmen.pfeiffer@nist.gov 

Dental resins 

Monomer synthesis 

Phelan, Jr., Frederick R. 

frederick.phelan@nist.gov 

Resin transfer molding: modeling and processing 

studies 

Viscoelastic flow modeling 

Flow in porous media 

Lattice Boltzmann methods 

Pochan, Darrin+

pochan@udel.edu 

SEM & TEM of polymeric materials 

Wide-angle and small-angle x-ray scattering 

Block copolymer phase behavior 

Popielarz, Roman+

Roman.Popielarz@nist.gov

Polymer synthesis and characterization 

Photo-polymerization 

Qiao, Fang+

Polymer mixing and compounding 

Liquid crystalline polymer/thermal plastic polymer 

mixing 

Roth, Steven C. 

steven.roth@nist.gov 

Piezoelectric polymer transducers-fabrication and 

applications 

Vacuum deposition of metals 

Calibration of polymer transducers 

Microcomputer interfacing 

Fluorescence measurements 

Schmidt, Gudrun+

Gudrun.Schmidt@nist.gov 

Polymer blends 

Liquid crystalline polymers 

Polymer-clay interaction 

Light and neturon scattering 

Schultheisz, Carl R. 

carl.schultheisz@nist.gov 

Failure of composites 

Experimental mechanics 

Torsional dilatometry 

Physics of polymer glasses 

Polymer rheology 
Staff

83

Schumacher, Gary E.* 

gary.schumacher@nist.gov 

Clinical dentistry 

Composites 

Dentin adhesives 

Sehgal, Amit+

amit@nist.gov 

Biomaterials, cell-surface biophysics 

Polymer thin films 

Polyelectrolytes and conducting polymers 

Structure and dynamics of polymer solutions 

Light scattering and fluorescence photobleaching 

recovery 

Shi, An-Chang +

shi@polymer.physics.mcmaster.ca 

Colloid theory 

Polymer phase transitions 

Sieck, Barbara A.* 

barbara.sieck@nist.gov 

Calcium phosphate compounds 

Chemical analysis 

Remineralization 

Simon, Carl G., Jr. 

carl.simon@nist.gov 

Biocompatibility 

Cytotoxicity 

Signaling in human platelets 

Bone marrow cell lineage/trafficking 

Skrtic, Drago* 

drago.skrtic@nist.gov 

Calcium phosphates as dental materials 

Liposome studies 

Smith, Archie+

archie.smith@nist.gov 

Combinatorial (High-Throughput) Experimental 

Design and Development 

Polymer Crystallization behavior 

Thin film Block copolymer behavior 

Nanofilled polymer behavior 

Electron, Atomic force, X-ray and light microscopies 

Snyder, Chad R. 

chad.snyder@nist.gov 

Polymer crystallization 

WAXD and SAXS of polymeric materials 

Thermal expansion measurements 

Thermal analysis of polymers 

 Dielectric measurements and behavior 

Soles, Christopher 

csoles@nist.gov

Viscoelastic properties of polymers 

Elastic and inelastic neutron scattering 

X-ray and neutron reflectivities 

Polymer thin films 

Son, Younggon +

Younggon.son@nist.gov 

Polymer Processing 

Polymer Phase Behavior 

Interfacial Phenomena

Stansbury, Jeffrey W. 

jeffrey.stansbury@nist.gov 

Synthetic chemistry 

Polymers and polymer composites 

Polymerization of expanding monomers 

Fluorinated polymers 

Polymerization kinetics 

Starr, Francis 

francis.starr@nist.gov 

Dynamics of filled polymers 

Slow dynamics in soft condensed matter 

Molecular dynamics simulations and parallel 

computing 

Takagi, Shozo* 

shozo.takagi@nist.gov 

Crystallography 

X-ray diffraction 

Calcium phosphate biomaterials 

Topical fluoridation 

De- and remineralization 

Tanaka, Jiro+

jiro.tanaka@nist.gov 

Dental composites 

IR & NIR spectroscopies 

Mechanical properties 

Tesk, John A. 

john.tesk@nist.gov 

Biomaterials: industrial relations 

Bond strength characterization 

Casting of alloys 

Strength of dental systems 

Thermal expansion and properties of dental materials 

Finite element studies 

Porcelain-metal systems 

Weibull analysis 

Wear testing, orthopaedic materials 

Reference biomaterials 
Staff

84

Tung, Ming S.* 

ming.tung@nist.gov 

Chemistry of calcium phosphate compounds 

Remineralization studies 

Standard reference materials 

VanderHart, David L. 

david.vanderhart@nist.gov 

Measurement of orientation in polymer fibers and 

films 

Solid state NMR of polymers 

Measurement of polymer morphology at the 2-50 nm 

scale 

Pulsed field gradient NMR 

Van Zanten, John H.+

jhvanzan@unity.ncsu.edu 

Complex fluids 

Polymer interfaces 

Scattering of light, neutrons & x-rays 

Biophysics 

Interfacial phenomena 

Scanning probe microscopy 

Viers, Brent 

brent.viers@nist.gov 

Polymer gels 

Rubber elasticity 

Inorganic organic hybrids 

Dendrimer networks 

Polymer stars 

Hydrogels 

Vogel, Gerald L.* 

gerald.vogel@nist.gov 

Dental plaque chemistry, chemistry of calcium 

phosphates 

Microanalytical techniques 

Wallace, William E. 

william.wallace@nist.gov 

Surface and interface behavior 

Ion beam and electron spectroscopies 

X-ray and neutron reflectivity 

MALDI mass spectrometry 

Wang, Francis W. 

francis.wang@nist.gov 

Photophysics and photochemistry of polymers 

Fluorescence spectroscopy 

Cure monitoring of polymerization 

Tissue engineering 

Wang, Howard +

hao.wang@nist.gov 

 Multiple phase transitions in polymer

Wetting, segregation and transport in polymer 

 Structure and dynamics in polymer gels 

Washburn, Newell 

newell.washburn@nist.gov 

Tissue engineering 

Polymer blends 

Biomaterial interfaces 

Viscoelastic properties of polymers 

Weir, Michael 

michael.weir@nist.gov 

Biomaterials 

Tissue engineering 

Biodegradable hydrogels 

Combinatorial analysis 

UV and fluorescence spectroscopy of polymers 

Wu, Wen-li 

wen-li.wu@nist.gov 

Neutron and x-ray scattering and reflectivity 

Electron microscopy 

Mechanical behavior of polymers and composites 

Polymer surfaces and interfaces 

Yurekli, Koray+

kyurekli@Jetson.uh.edu 

Polymer nanocomposite 

Phase separation 

Thin films and interfaces 

Neutron and light scattering 

Xie, Baosheng+

Testing micro tensile and micro-sheer bond strength 

Xu, Huakun*

hockin.xu@nist.gov 

Silver alloy alternative to amalgam 

Wear and fatigue 

Fiber and whisker reinforcement 

Zhang, Yubao+

yubao.zhang@nist.gov 

Dynamic light scattering 

Polyelectrolytes 

Small angle neutron scattering 

*Research Associate 

+

Guest Scientist 
85

Organizational Charts
86

Polymers Division

Organizational Charts 

Donna Stutso

Administrative Officer

Bruno Fanconi

Deputy Chief

C. Chiang

E. Lin

J. Obrzut

C. Snyder

E. Chen

H. Lee

N. Noda

R. Popielarz

Electronics Materials

Wen-li Wu, Group Leader

854.02

B. Webb, Secretary

J. Antonucci

J. Hsii

T. Huang

C. Simon

C. Khatri

A. Mizukami

S. Yoneda

Biomaterials

Francis Wang, Group Leader

854.03

J. Burton, Secretary

M. Chiang

J. Dunkers

R. Hedden

R. Jones

J. Lenhart

C. Soles

F. Starr

W. Wallace

Method Development

Wen-li Wu

S. Bhatt

W. Blair

C. Guttman

C. Schultheisz

J. Tesk

R. Goldschmidt

J. Maurey

S. Wetzel

Standards & Data

Bruno Fanconi

B. Bauer

A. DeReggi

J. Douglas

S. Glotzer

E. Hobbie

C. Jackson

F. Khoury

D. Liu

W. McDonough

P. McGuiggan

D. VanderHart

Internal Capabilities

Eric Amis, Acting

Characterization & Measurement

854.01

B. Webb, Secretary

K. Beers

A. Crosby

N. Washburn

M. Weir

K. Ashley

G. Cantoni

A. Sehgal

A. Smith

K. Yurekli

Multivariant Measurement Methods

Alamgir Karim, Group Leader

854.06

K. Hollingsworth, Secretary

G. Holmes

D. Hunston

A. Nakatani

F. Phelan

E. Feresenbet

J. He

G. Schmidt

H. Wang

Multiphase Materials

Charles Han, NIST Fellow

854.04

J. Burton, Secretary

A. Bur

K. Flynn

S. Roth

F. Qiao

Y. Son

Processing Characterization

Kalman Migler, Group Leader

854.05

K. Hollingsworth, Secretary

Polymers Division

Eric Amis, Division Chief

854.00

Janice Green, Division Secretary
NISTIR 6596—POLYMERS DIVISION: FY 2000 PROGRAMS AND ACCOMPLISHMENTS