i

Materials Science and

Engineering Laboratory

FY 2003 Programs and

Accomplishments

Polymers

Division

Eric J. Amis, Chief

Chad R. Snyder, Deputy

NISTIR 7016

September 2003

National Institute of

Standards and Technology

Arden L. Bement, Jr.

Director

Technology

Administration

Phillip J. Bond

Undersecretary of

Commerce for Technology

U.S. Department

of Commerce

Donald L. Evans

Secretary
ii
iii

Table of Contents

Table of Contents

Executive Summary ...................................................................................................................1

Technical Highlights:

Reaching Outwards ............................................................................................................3

A Fully Automated Peak Picking and Integration Algorithm

for Mass Spectral Data .......................................................................................................6

Pore Size Distributions in Low-k Dielectric Thin Films

from SANS Porosimetry .....................................................................................................8

Critical Dimension Metrology of Nanoscale Structures with

Small Angle X-ray Scattering ............................................................................................10

High-throughput Measurements of Elastic Moduli of

Polymer Thin Films ...........................................................................................................12

Elastic Flow Instability in Polymer-Dispersed Carbon Nanotubes ...................................14

Scaffold Structure and Cell Function through Multi-Modal Imaging

and Quantitative Visualization ...........................................................................................16

Macromolecular Dynamics via Inelastic Neutron Scattering ...........................................18

Advanced Manufacturing Methods .........................................................................................21

Processing Flows & Instabilities .......................................................................................22

Combinatorial Methods............................................................................................................ 23

Polymer Formulations: Fluidic Devices and Scattering

Measurements for High Throughput Materials Research ................................................24

Combinatorial Epoxy Curing Library: Correlating Network

Formation, Chemical Conversion, and Adhesion .............................................................. 25

NIST Combinatorial Methods Center (NCMC)

A Partner in Accelerating Materials Research ............................................................ 26

Interface of Materials with Biology ........................................................................................27

Bioactive Polymeric Composites for Mineralized

Tissue Regeneration ..........................................................................................................28

High-Throughput Biocompatibility Screening of Polymer Blends .................................... 29

Measurement of Cellular Response to Three-Dimensional

Scaffolds for Tissue Engineering ...................................................................................... 30
iv

Table of Contents

Materials for Micro- and Opto-Electronics .............................................................................31

Characterization of Porous Low-k Dielectric Constant Thin Films..................................32

Polymer Photoresists for Next-Generation Nanolithography ...........................................33

Dielectric Measurements of Polymer Composite Films

in the Microwave Range ...................................................................................................34

Materials Structure Characterization ......................................................................................35

Coherent Anti-Stokes Raman Micro-spectroscopy (μ-CARS)

for Understanding Tissue Growth in Scaffold Constructs ................................................36

Polymer Standards ............................................................................................................ 37

Polyolefin Mass Spectrometry ..........................................................................................38

Nanocharacterization ...............................................................................................................39

Process Monitoring of Polymer Clay Nanocomposites ....................................................40

Nanomanufacturing ...........................................................................................................41

Polymers Division FY03 Annual Report Publication List ........................................................43

Polymers Division ....................................................................................................................53

Research Staff......................................................................................................................... 54

Organizational Charts ..............................................................................................................63
1

Executive Summary

Executive Summary

Measurement is at the core of understanding, and at

NIST, we take pride in both our fundamental metrology

and our creative investigations to establish the essential

underlying scientific foundation. In both respects,

I am pleased to report that this has been an excellent

year for the scientists in the NIST Polymers Division.

As usual, this annual report is organized to briefly

describe the major project areas where we have focused

our efforts within the programs of the Materials Science

and Engineering Laboratory. In addition, we have

highlighted several specific successes within the NIST

2010 Strategic Focus Areas of information and knowledge

management, nanotechnology, and health care.

Information and knowledge management are

critical to a metrology system both for cataloging

and for interpreting data. Our first technical highlight

addresses this issue for mass spectrometry by

introducing a robust data analysis tool with no

user-selected parameters that has been developed in

collaboration with the NIST Information Technology

Laboratory. The benefits to this algorithm are

that it eliminates user bias from the analysis, and it

allows automated processing of large quantities of

data. In addition to advancing our goal of developing

absolute molecular mass Standard Reference Materials,

and extending the reach of polymer mass spectrometry

for advanced quantitative applications, we have already

seen that this tool will be used in the growing application

of mass spectrometry for proteomics research.

The National Nanotechnology Initiative identifies

Nanoscale Instrumentation and Metrology as one

of the “Grand Challenges,” and in this area, NIST has

a major role. This year, four of our highlights focus

on this grand challenge. To aid the semiconductor

industry in their search for new low-k dielectric

materials, we have extended our definitive characterization

work with new methods to determine the distribution

of pore sizes and to reveal extremely subtle material

characteristics that have been inaccessible by other

measurements. For the lithographic process itself,

we have developed new techniques to characterize

pattern uniformity and defects even for the dense

and high aspect ratio patterns that will enable the next

generation of semiconductors and nanotechnology.

It is also clear that as electronic devices continue to

shrink, their mechanical properties will be increasingly

important. There have been a number of approaches

to this problem, and our contribution this year raises

the bar with a unique method that provides rapid and

quantitative characterization of the elastic modulus of

supported films. Finally, we have taken advantage of

our expertise in multiphase flow to describe the critical

effects of processing on the dispersion and orientation

of multiwall carbon nanotubes in polymer solutions.

In the third NIST Strategic Focus Area of health

care, we are highlighting two relatively new projects

related to tissue engineering, which is a major

emphasis for NIST that was announced in our

report last year. The first of these projects originated

from the non-destructive imaging method of optical

coherence tomography that we had used for studies

of polymer-fiber composites. We have now extended

the method, based on a combination of optical

coherence and confocal fluorescence microscopy,

to develop powerful tools for in situ measurements

of 3D structure and biological activity within tissue

engineering scaffolds. In addition to the qualitative

trends that can be studied by simply observing the

images, we are demonstrating techniques capable of

extracting quantitative, chemically specific data from

the images. The final highlight describes a study,

completed at the world-class inelastic neutron

scattering facilities of the NIST Center for Neutron

Research, to observe dynamics in macromolecular

materials. From these measurements, we are able to

investigate the mechanisms of cryopreservation used

for stabilization of proteins, pharmaceuticals, and

biomaterials. Although these are early stage projects,

both of them demonstrate how we expect to leverage

state-of-the-art measurement science at NIST to

address critical needs for biomedical materials.

The Polymers Division has now grown to over 100

staff, postdoctoral associates, and guest researchers,

and together, we continue to foster productive and

dynamic project teams. We take pride in the creativity

of NIST scientists, from the most senior staff of

44 years to the newest postdoctoral researcher who

arrived last week. It is always difficult for me to

choose from all that was completed in the past year

for the few items we can highlight. Please visit our

website for more details on current work, copies of

our publications, and to check on a new link that we

refer to as “Out-from-Under-the-Radar.” As always,

I welcome your comments.

Eric J. Amis

Chief, Polymers Division
2
3

Highlight

Reaching Outwards. . .

“If a tree falls in the forest and no one is there

to hear it, does it really make a sound?”

“If research is performed and no one is there

to hear it, does it really matter?”

A strong outreach effort assures that people are

hearing about what you are doing. It also should

determine if they actually CARE about what you

are doing.

Who cares?” is a question that arises when

 considering the impact of science and engineering.

To ensure that people do care about, and are aware

of, the activities of our Division, we maintain a

rather strong outreach program. In considering

outreach efforts, the three obvious “modes” include

disseminating, collaborating, and exchanging.

Dissemination is one of the most popular techniques

for outreach in the physical sciences. The paramount

example of the dissemination mode is publication in

peer-reviewed archival journals. The limitation to this

method, of course, is that you can never really be sure

how many people read and learned from the papers.

Like other researchers, we do exploit this method of

outreach, and our publication rate is high. However,

there are several other avenues that we exploit including

NIST Special Publications and web services of various

types. The collaborative mode of outreach is probably

the most productive method of outreach. This method

includes workshops, standards committees, special

interest groups, and partnerships. The last mode of

outreach is exchange. This mode tends to generate

long-term partnerships and collaborations; examples

of this range from lecturers who we have invited to

give presentations to us to summer students who gain

laboratory experience at an early age. On the following

pages, we will present specific examples of our

outreach efforts to give you a better understanding

of exactly how we do business.

Dissemination

This year, we published a NIST Recommended

Practice Guide, Capacitance Cell Measurement of

the Out-of-Plane Expansion of Thin Films (NIST

SP 960-7). This guide is intended for use in

microelectronics where accurate measurement of

thermal expansion is important in the design of interlevel

dielectrics. This guide was developed to make this

sensitive metrology more accessible by detailing the

construction and use of the capacitance-based metrology

for thermal expansion measurements. It has been made

available as both a hard copy guide and electronically

on the web. We are also using the web to further

disseminate our research by posting our publications on

our website (www.nist.gov/polymers). The database

is searchable by research group, year of publication,

subject term, author, and keyword. To complement

the publications, we also post information regarding

our ongoing research projects, highlights of recent

research, and information on our staff’s research

interests and expertise. Additionally, we have added

a database that consists of methods, taken largely

from the peer-reviewed scientific literature, for

matrix-assisted laser desorption ionization (MALDI)

mass spectrometry on a wide variety of synthetic

polymers. The current listing contains over

100 recipes. We encourage you to visit our website

to learn more about these items.

Collaboration

One of the most prominent examples of the

collaborative mode during the past fiscal year was the

large number of workshops ranging across most of

the Division’s programmatic areas. To demonstrate

the continuous nature of this effort, we have listed the

workshops chronologically, rather than programmatically.

Workshops

On October 7–8, 2002, the NIST Combinatorial

Methods Center (NCMC) held its second member’s

workshop entitled “Adhesion and Mechanical Properties.”

Over 40 member representatives attended the workshop

from 14 major industrial companies. The first

day focused on recent advances in combinatorial

adhesion testing developed by the NCMC, including

combinatorial peel testing and a multilens contact

adhesion test. The second day centered on the topic

of mechanical properties. The morning session

concluded with practical laboratory demonstrations

of the NCMC’s gradient library fabrication techniques,

analysis and instrumentation including flow coating,
4

Highlight

composition gradient libraries for viscous formulations,

combinatorial lens adhesion measurements, combinatorial

peel testing, and polymer composition gradients using

melt extrusion. The afternoon session consisted of a

panel discussion focusing on member needs and future

directions of the NCMC.

On November 7–8, 2002, experts in the field

of mass spectrometry met at NIST to discuss

measurement barriers to quantification of molecular

characteristics of synthetic polymers. It also featured

a problem-solving session in which industrial users

of the method presented measurement challenges

and problems specific to their applications.

The workshop was organized according to key steps

in the MALDI-MS measurement process — sample

preparation, volatilization and ionization, ion detection

and data analysis. Participants concluded that

experimental confirmation of key molecular events

during the volatilization and ionization processes was

needed. A report on the workshop is published in

the NIST Journal of Research, available on the Web.

On January 15, 2003, Polymers Division researchers

were invited to International SEMATECH (ISMT), an

industrial consortium of semiconductor manufacturing

companies, to present results from unique measurement

methods for the evaluation of materials factors

impacting the ultimate resolution of next-generation

photoresists to its Resist Advisory Group. The Resist

Advisory Group audience represents a large fraction of

the companies directly involved with the development

and production of the sub-100 nm structures in current,

integrated circuits. Interaction with the participants

provided useful feedback on the timeliness, relevance,

and quality of the measurement methods developed by

NIST to the further development of next-generation

lithographic materials.

On January 27–28, 2003, a two-day workshop on

scanning probe microscopy (SPM) was held at NIST.

SPM techniques are especially good for examining

materials locally for a wide range of material properties,

including surface topology, surface tribology, elastic

properties, ferroelectric domain structure, electric

potential and impedance at surfaces, and the atomic

structure of crystals at surfaces. The primary purpose

of the workshop was to familiarize people with the

many uses of the technique. Guests from government

labs included the FDA, USDA, and NRL, and guests

from industry included GE and Millenium Chemicals.

On February 19, 2003, the NCMC co-organized

a full day workshop that was held in conjunction

with the Knowledge Foundation’s “COMBI 2003 —

Combinatorial Approaches for New Materials Discovery”

meeting (February 20–21, 2003, in San Jose, CA).

The NCMC pre-conference seminar entitled,

“High-Throughput Materials Informatics:

Knowledge Acquisition for Better Materials,” was

attended by over 30 representatives from industry

and academia. The seminar examined issues

concerning the enormous amounts of data created by

combinatorial/high-throughput materials research and

the conversion of such data into usable information.

On March 20–21, 2003, the Polymers Division

hosted the second “NIST–KIPS Symposium on

Polymer Science.” (KIPS is the acronym for the

Kyoto Institute of Polymer Science.) This bi-annual

conference/workshop builds bridges and fosters

collaborations between polymer scientists in the U.S.

and those in Japan. Approximately 100 attendees,

including 16 from KIPS and the remainder from U.S.

universities and NIST, participated in intensive lectures,

discussions, and poster sessions which covered the

full range of polymer science.

On May 22–23, 2003, the NCMC held its third

member’s workshop entitled “Combinatorial Informatics.”

Over 30 member representatives from 16 companies

and universities and 26 NIST staff attended the

workshop. The goal of the workshop was to illuminate

needs in combinatorial and high-throughput informatics

research, in particular in combi-oriented data standards

called for by the NCMC industrial community. The

workshop culminated in a panel discussion aimed at

initiating a process for the establishment of mutually

beneficial data interchange standards. As a result,

the Combinatorial Materials Research Data Standards

(CMRDS) Working Group was formed. The final

sessions of the workshop concerned NCMC research

activities and services. Here, the laboratory informatics

system being developed at the NCMC core facility

was described.

On June 5, 2003, two Polymers Division

researchers presented invited lectures on recent

advances in the characterization of the structure and

properties of nanoporous low-k dielectric materials at

the “Low-k Porosimetry Workshop” sponsored by

ISMT in June 2003. The NIST presentations

complemented other presentations from university,

industry, and governmental laboratories. NIST

participation in the workshop helped facilitate

discussion of all available measurement methods for

characterizing next-generation dielectric materials.

Standards Developing Organizations (SDO’s)

A major part of NIST’s Congressionally mandated

mission is the development of standards to improve

commerce and facilitate trade. For this reason, one

of our more active collaborative outreach methods

is through our participation in standards committees.

Rather than enumerate all of our memberships, we

have chosen a few examples that range across our

programmatic areas with different levels of participation.
5

Highlight

A draft standard protocol for determination of

molecular mass and molecular mass distribution

of atactic polystyrene by matrix-assisted laser

desorption/ionization — time of flight — mass

spectrometry has been distributed to members of

ISO/TC 35/SC 10 on June 6, 2002 for balloting and

is also under review by ASTM. The standard method

will be useful in comparisons of mass spectrometers,

sample preparation for mass spectrometry, and data

analysis. The method was developed under the

auspices of the Versailles Project on Advanced Materials

and Standards (VAMAS) by an international team led by

a researcher from the Polymers Division. The protocol

is derived from a procedure used in an international

interlaboratory comparison of analysis of polystyrene

by MALDI MS. The polystyrene analyzed in the

interlaboratory comparison was also issued as a

NIST Standard Reference Material in FY 2003.

A Polymers Division researcher chairs an IPC task

group for the development of standard test methods for

embedded passive devices. In this role, NIST guides

industrial partners in developing and drafting standard

test documents and manuals for this emerging materials

area. This close working arrangement allows for direct

feedback of standard measurement method development

that will positively impact the electronics industry.

In addition, new technical challenges have furthered

the development of needed standard test methods.

A wide variety of standards-related activities are

ongoing in the area of biomedical devices and materials.

Polymers Division researchers are actively involved in

ASTM committee F04 (Medical and Surgical Materials

and Devices) to expedite introduction of reference tissue

scaffolds to aid in the development of characterization

methods for their structure and properties. Additionally,

Division researchers have been involved in planning an

ASTM workshop on cleanliness of medical implants in

2003, a symposium on cell-materials signaling in 2003,

and several other workshops and symposia in future years.

Further information on health care related standards in

the Division is provided in the Polymer Standards project

write-up.

Special Interest Groups (SIGs)

One of the collaborative methods that we use

rarely, and only when it is appropriate, is through SIGs.

One example of this can be found in our Processing

Characterization efforts. Due to the complexity of the

phenomena occurring during polymer manufacturing,

precise measurements of polymer processing parameters

is difficult. Yet the ability to precisely measure these

properties is necessary in order to achieve six sigma

manufacturing goals. In recognition of this problem,

a Polymers Division scientist has established a SIG

devoted to real-time measurement issues. This group

meets every year at the Society of Plastics Engineer’s

annual technical meeting. At this year’s meeting, 15

papers were presented on process monitoring using a

variety of techniques, such as ultrasonics, fluorescence,

and analytical mass spectroscopy. Dissemination of

these on-line measurement concepts through the SIG

allows manufacturers to achieve greater quality control.

Exchange

In FY 2003, we had 35 invited lecturers in to give

presentations on cutting edge research in all of the

Division’s programmatic areas as well as in several

new strategic directions. As a complement to the

information provided in the lectures, informal meetings

are typically held during the remainder of the day for

our staff to exchange information with the visitor.

In addition to these short-term exchanges, every year

we bring in students to collaborate on research projects.

The students have varying levels of experience, ranging

from high school students through undergraduates

to graduate students. By way of example, we hosted

three students from Montgomery Blair High School

(Montgomery County, MD) this year. Two assisted

in polymers formulations research, while another

returned to co-author an invited article for Microscopy

Today based on his work from the previous summer.

In addition, a University of Maryland Baltimore County

(UMBC) undergraduate, introduced to NIST through

the Minority Access Program, worked on combinatorial

informatics and mechanical properties projects. We also

have active collaborations with guest researchers from

other institutions, and through the National Research

Council (NRC)/NIST postdoctoral research program,

we are constantly exchanging new ideas and techniques.

In the past two fiscal years, we have received 18 new

postdocs through this program. Finally, this year NIST

and the National Institutes of Health (NIH) have initiated a

joint postdoctoral research program, and several Division

researchers have research opportunities through this

program. (Further information is available about the

joint postdoctoral program on the National Academies

website at www.nationalacademies.org by searching

for “NIH/NIST.”)

A Final Note. . .

As you may have noticed, we left out one noticeable

example of outreach, and that is through the publication

of our Annual Report. We hope that you enjoy the

following technical highlights and project reports, and we

look forward to reaching out to you further in the future.

For More Information on this Topic

Chad R. Snyder (Polymers Division, NIST)

www.nist.gov/polymers
6

Technical Highlights in Information/Knowledge Management

A Fully Automated Peak Picking and Integration Algorithm

for Mass Spectral Data

A numerical algorithm is described that

accurately locates and calculates the area

beneath peaks from real mass spectral data using

only reproducible mathematical operations and no

user-selected parameters. Such a fully automated

algorithm was required for rapid and repeatable

processing of mass spectral data containing

hundreds of peaks. By working without any user

input, it both saves operator time and eliminates

operator bias. The first criterion is desirable

when processing large amounts of data (for

example in proteomics research). The second

criterion is necessary to the Polymer Division’s

goal of creating an absolute molecular mass

distribution synthetic polymer Standard Reference

Material where operator bias in the data analysis

cannot be tolerated.

William E. Wallace and Anthony J. Kearsley

Aunified collection of algorithms has been developed

 that accurately locates peaks and calculates their

area using only reproducible mathematical operations

and no user-selected parameters. As shown in Figure 1,

the method consists of three steps: 1) statistical

characterization of the data set and an analyte-free

background spectrum; 2) data set segmentation to

determine “strategic points”; and 3) deflation of the

number of strategic points guided by the statistical

properties of the data sets. The final deflated set of

strategic points consists of groups of three points that

define the beginning, center, and end of each peak in

the data. For closely spaced peaks, the strategic point

that defines the end of one peak may also define the

beginning of the next. Finally, a polygonal fitting

routine is used to calculate relative peak area.

The time-series segmentation algorithm at the

heart of the method consists of two steps. The first

portion (2a) requires the selection of the strategic

points. These points are selected based on an iterative

procedure that identifies points whose orthogonal

distance from the end-point connecting line segment

is greatest. Once a point with greatest orthogonal

distance from the mean has been identified, it joins the

collection of strategic points and, in turn, becomes an

end-point for two new line segments from which a

point with greatest orthogonal distance is again found.

This numerical scheme is performed until the greatest

orthogonal distance to any end-point connecting line

segment drops beneath a prescribed threshold value.

This threshold value is calculated from the statistical

properties of the data set. The selection of these points

does not require equally spaced data. The second

phase of the algorithm (2b) requires the solution of an

optimization problem, specifically, locating strategic

point heights (that is, adjusting strategic y-axis values

associated with strategic x-axis values) that minimize

the sum of orthogonal distance from raw data. This

problem is a nonlinear (and non-quadratic) optimization

problem that can be accomplished quickly using a

modern nonlinear programming algorithm. Parts 2a

and 2b are collectively called the Kearsley–Wallace

method, which is an extension of the earlier

Douglas–Peucker method.

Consider the polystyrene matrix-assisted laser

desorption ionization time-of-flight mass spectrum

shown in Figure 2 (black) and its complementary

matrix-only background spectrum (red). The resultant

strategic points (green) defining peak beginning, center,

and end, and the relative peak areas (blue) are also

shown. Note that ion intensity is on a logarithmic scale,

Figure 1: Method Flow Chart.
7

Figure 2: Sample polystyrene MALDI TOF mass spectrum

(black) and its complementary matrix-only background

spectrum (red).

Technical Highlights in Information/Knowledge Management

thus the small peaks are significantly smaller than

the main series of peaks. The analysis of this was

done without operator intervention of any sort.

The only input provided was the spectrum to be

analyzed and an analyte-free spectrum to determine

inherent instrument noise. The noise has both

chemical (e.g., improperly time-focused ions) and

electronic (e.g., detector dark current) components.

These noise elements span a wide frequency range

and cannot simply be smoothed out of the data

without distorting peak shape (and, therefore,

peak area). Our experience shows that the power

spectrum of the noise cannot be predicted solely

from the experimental conditions; therefore, blind

application of smoothing and/or filtering algorithms

will unintentionally remove information from

the data.

Some of the additional strengths of this method

include the fact that it requires no knowledge of peak

shape, and, furthermore, it requires no preprocessing

of the data, i.e., smoothing or baseline correction

with their resultant distortion of peak area. Lastly,

the method does not require equal spacing of data

points (e.g., time-of-flight data can be processed in

mass-space where the points have a square root

spacing). The one significant weakness is that the

method is more successful and efficient if a blank

(analyte-free) spectrum is used to calibrate instrument

background noise. (However, such a background

spectrum is not strictly required.)

Future plans include the creation of a publicly

accessible, secure Web-server application for

on-line, real-time application of the algorithm. We

will also relay the method to other standards-setting

organizations for comment and to commercial

software vendors for implementation in their

products. Lastly, we have begun to tackle the

much more subtle problem of automated,

operator-independent baseline compensation.

For More Information on this Topic

W.E. Wallace, C.M. Guttman (Polymers Division,

NIST); A.J. Kearsley, J. Bernal (Mathematical and

Computational Sciences Division, NIST)
8

Technical Highlights in Nanotechnology

Pore Size Distributions in Low-k Dielectric Thin Films

from SANS Porosimetry

The microelectronics industry is testing a wide

variety of porous low-dielectric constant (“low-k”)

materials for future use in integrated circuits.

To understand low-k thin film properties, a

quantitative analysis of pore size distribution

is vital. The Electronics Materials group has

developed a new approach to this challenging

problem based on a small angle neutron scattering

(SANS) porosimetry technique. The new technique

quantifies pore size distribution and reveals subtle

material characteristics inaccessible to other

measurement techniques.

Barry J. Bauer and Ronald C. Hedden

As feature size on integrated circuits decreases to

 below 100 nm, electrical crosstalk, or interference

between interconnects, becomes a major obstacle to

device performance. A need has arisen to develop

improved electrical insulating materials for the next

generation of microelectronic devices. Silicon dioxide

and fluorosilicate glass, the insulators used in today’s

devices, have dielectric constants (k) of about 4.2 and

3.7 respectively, but materials with dielectric constants

of 2.2 or lower will be needed by 2007. However, it

has proven difficult to improve existing materials by

changing their chemical structure.

Much of the recent developmental efforts in

low-k dielectrics involve production of nanoporous

thin films. By introducing tiny air-filled pores into

the material, the bulk dielectric constant is lowered

because air has a dielectric constant of 1.0. The

microelectronics industry is testing a wide variety of

porous low-dielectric constant (“low-k”) materials,

including both organosilicate and organic polymer

types. To understand the basis for their physical

properties, detailed structural characterization is

essential. Specifically, quantitative characterization

of the pore size distribution is a critical issue because

pore size impacts mechanical, thermal, and barrier

properties of the films. Because pore size is very small

(< 10 nm) and pore volume fraction is high (0.1 to 0.5),

microscopy techniques are generally insufficient for

evaluation of pore size distribution.

A new approach to pore size determination

combines the established science of capillary

porosimetry with a powerful analytical technique,

small angle neutron scattering (SANS). Capillary

porosimetry is an established experimental technique

applicable to determination of pore size distributions.

The porous material is exposed to the vapor of a “probe

solvent,” and pores fill with liquid solvent by capillary

condensation. An adsorption isotherm is constructed

by measuring solvent uptake as a function of partial

pressure. In general, filling of the pores with solvent

is size-dependent; the smallest pores fill first as solvent

partial pressure is increased. Alternatively, the sample

temperature may be varied while solvent partial

pressure is held constant. Optical, x-ray, or gravimetric

techniques may be employed to measure solvent uptake.

Figure 1 shows solvent adsorption curves obtained by

specular x-ray reflectivity (SXR) for an organosilicate

type low-k material.

A limitation of capillary porosimetry is that pore

size is usually not directly measured but is calculated

by applying a physical model to the adsorption

data. Serious ambiguities result when hysteresis

phenomena are observed, which is normally the case

for nanoporous materials. In addition, physical models

for adsorption may fail when pores are very small, as in

the low-k dielectrics. Conventional analysis of capillary

porosimetry data, therefore, can provide only qualitative

comparisons between low-k materials, not quantitative

pore size distributions. However, a great improvement

to the technique is possible by using small angle neutron

Figure 1: Solvent adsorption data for an organosilicate low-k

dielectric measured by x-ray reflectivity. Porosimetry is conducted

by two methods: under isothermal conditions while varying

solvent partial pressure in a carrier gas (green, black), or in a

saturated solvent atmosphere while varying sample temperature

(red, blue).
9

Technical Highlights in Nanotechnology

scattering (SANS) to observe the adsorption process.

By monitoring the pore filling and unfilling with SANS,

important characteristics of the pore size distribution

can be quantified irrespective of hysteresis phenomena.

To facilitate SANS porosimetry experiments,

a programmable atmospheric control device was

constructed that uses mass flow controllers to deliver

solvent vapor in air to a flow-through sample cell.

The partial pressure P of the solvent can be varied

from 0.0 (pure air) to P* (saturated solvent vapor).

The sample may also be exposed to solvent vapor at

a constant partial pressure P while sample temperature

is varied, effectively changing P*.

The first stage of neutron porosimetry is a

“contrast match point” determination. The pores

are filled with solvent mixtures of variable neutron

scattering length density (SLD). The solvent SLD is

varied by mixing hydrogen- and deuterium-containing

analogs of the solvent. The scattered intensity I(q)

from the solvent-filled, porous material depends on

the difference in SLD or “contrast” between the

solvent and the matrix. The solvent SLD is varied

systematically, and the scattered intensity I(q) is

measured at each composition. If the material is

homogeneous in atomic composition and all of the

pores fill with solvent, a contrast match solvent

composition exists for which I(q) becomes zero over

all q. If the material has inhomogeneities in its atomic

composition, or if some of the pores are not filled by

solvent (“closed pores”), a contrast match point will not

be observed. SANS porosimetry is more applicable to

samples with a true contrast match point, as subsequent

data analysis is complicated by inhomogeneities.

The second stage of the measurements is

porosimetry using solvent vapor of the contrast match

composition. SANS data are collected as the partial

pressure of the probe solvent is increased (sorption)

and decreased (desorption). When pores fill with the

contrast match liquid, their SLD matches the sample

matrix, so the SANS measurement yields the size of

only the “empty” pores. Thus, as solvent partial

pressure is increased, pore size is measured for

sub-populations of pores of increasingly large size.

If the volume fraction of the solvent in the film

is also measured as a function of partial pressure,

then average pore size and pore volume fraction are

simultaneously known. X-ray reflectivity porosimetry

allows such measurement with high precision and

is a powerful complement to SANS porosimetry.

Figure 2 shows combined results from both techniques:

pore size from SANS is plotted vs. empty pore

volume fraction from SXR. The data are essentially

unaffected by hysteresis phenomena within the limits

of uncertainty of the experiment. When all pores are

empty, the SANS measurement gives the average pore

size for the entire distribution. As pores are filled,

the upper end of the pore size distribution is probed

because only the larger pores are empty and contribute

to I(q) from SANS. For the sample shown in Figure 2,

the average pore size is about 60 Å, but the sample

contains some pores of 80 Å or larger. By using

capillary porosimetry to isolate the scattering from the

largest pores, sub-populations of large pores within a

low-k material can be readily identified, provided their

concentration is high enough to make a measurable

change in the scattering. Such information is valuable

to the low-k integration effort because large pores are

a leading cause of device failure.

Figure 2: Size information (average chord length) from SANS

porosimetry plotted vs. volume fraction empty pores from x-ray

reflectivity. The scattering data contain size information related to

the average size of only the empty portion of the pores. As solvent

partial pressure is increased from P/P*= 0.0 to P/P*= 1.0

(saturated solvent vapor), pores fill with liquid solvent in order

from smallest to largest. As P/P* approaches 1.0, the scattering

from the largest pores is probed.

The SANS porosimetry technique allows

characterization of pore size distribution without a need

for a physical model for adsorption. SANS porosimetry

is perhaps the most quantitative technique available

today for characterizing pore size distribution in

nanoporous low-k thin films.

For More Information on this Topic

B. Bauer, H. Lee (Polymers Division, NIST);

R. Hedden (Department of Materials Science and

Engineering, The Pennsylvania State University)
10

Technical Highlights in Nanotechnology

Critical Dimension Metrology of Nanoscale Structures with

Small Angle X-ray Scattering

The continued reduction in pattern sizes

throughout the semiconductor industry will

soon require new metrologies capable of high

throughput non-destructive measurements

of dense, high-aspect ratio patterns with

sub-nanometer resolution. In collaboration with

industrial partners, we are developing a metrology

based on Small Angle X-ray Scattering (SAXS)

to quickly, quantitatively, and non-destructively

measure the smallest, or “critical,” dimensions

expected in the next two technology nodes with

sub-nanometer precision. Quantities of interest

include critical dimension, pattern sidewall

angle, statistical deviations across large areas,

and quantitative measures of pattern sidewall

roughness. These efforts are driving toward the

specification of a laboratory scale device capable

of providing pattern dimensions during routine

tests of fabrication processes.

Ronald L. Jones and Wen-li Wu

The drive to reduce feature size to the sub-100 nm

 regime continues to challenge traditional metrology

techniques for pattern characterization. Determination

of the quality of the patterning process currently

depends on the production of test patterns, such as line

gratings, and evaluating dimensional control and the

number of defects. As pattern sizes decrease, existing

metrologies based on scanning electron microscopy

and light scatterometry face significant technical

hurdles in quantifying pattern dimensions and defects

in dense, high-aspect ratio patterns used in modern

semiconductor circuitry. There are currently no clear

solutions to pattern quality measurement for future

technology nodes with dimensions on the order of

30 nm and dimensional control to less than a nanometer.

To address these issues, NIST is developing a

transmission x-ray scattering-based method capable

of angstrom level precision in critical dimension

evaluation over large, (50 x 50) μm, arrays of nanoscale

periodic structures. In contrast to light scatterometry,

Small Angle X-ray Scattering (SAXS) is performed

in transmission using a sub-Angstrom wavelength.

With a wavelength more than an order of magnitude

smaller than the pattern size, the patterns can be

analyzed using methods traditionally employed in

crystallographic diffraction. The high energy of the

x-ray beam allows the beam to pass through production

quality silicon wafers without requiring a specialized

sample environment (ultrahigh vacuum). While current

measurements utilize the flexibility and wide array of

instrumentation available at a synchotron source, initial

results and the commercial availability of x-ray sources

and detectors suggests the technique is portable to a

laboratory scale device.

As shown in the schematic below, the

patterned sample is placed in an x-ray beam where

the transmitted intensity is measured as a function

of the scattering angle, 2θ, on a 2-D detector.

The intensity is then fit to models describing the

average pattern shape. To save valuable space

within the total patterned area, industrial test patterns

are typically smaller than (50 x 50) μm. Using a

monochromator to define the wavelength and two

sets of beam-defining slits, beam footprints of

approximately (40 x 40) μm have been successfully

demonstrated. In contrast to 1-D techniques such as

light scatterometry, the use of a 2-D detector allows

the simultaneous characterization of all dimensions

for patterns such as vias (arrays of cylinders standing

perpendicular to the surface) and via pads (arrays

of rectangles). In addition to measuring the pattern

dimensions along the substrate plane, measurements

at varying sample rotation angles, ω, can be used to

reconstruct the average 3-dimensional pattern shape.

In collaboration with International SEMATECH,

recent SAXS measurements of line gratings have

demonstrated the capability of SAXS to measure

fabricated patterns of thermally grown oxide with

overall dimensions designed for current metrologies.

The resulting detector image is a series of diffraction

peaks along a single diffraction axis perpendicular

to the orientation of the grating. The number of

observable diffraction orders is in part determined by

the pattern quality. The observation of over 30 orders

of diffraction suggests the relatively high quality

of these patterns and provides ample data for

Figure 1: Schematic of SAXS geometry, showing incident and

scattered beams (red lines), sample with pattern oriented at

rotation angle ω and 2-D detector (right).
11

Technical Highlights in Nanotechnology

high-precision analysis. In addition, the number of

observable diffraction orders serves as an immediate

measure of pattern quality, termed a SAXS “fingerprint.”

With a measurement time on the order of a second,

dose exposure matrices commonly used to evaluate

optical imaging conditions can potentially be evaluated

in a matter of minutes.

In addition to the SAXS “fingerprint,” quantitative

information is obtained through model fitting of the

data. In contrast to reflection-based techniques, the

models used here are relatively simple. Quantitative

measures of the pattern repeat period and the line width

are therefore obtained rapidly and precisely. For these

samples, SAXS data have provided sub-nanometer

precision in both average repeat distance and average

line width. The precision of this measurement is in

part dictated by the number of observable diffraction

orders, which is in turn limited by the instrumental

resolution and pattern quality. Ongoing studies will

compare these results with measurements from light

scatterometry, atomic force microscopy, and scanning

electron microscopy.

In collaboration with the IBM T.J. Watson

Research Center, the effects of specific types of

defects in patterns on the resulting SAXS image are

being explored. Shown in Figure 2, a simple model of

an ideal line grating captures the main features of

the diffraction spots; however, additional information

is observed in the 2-D image perpendicular to the

diffraction axis. Streaks of intensity emanating

from diffraction peaks are visible near the beamstop.

These streaks are indicative of deviations from the

ideal grating and may provide information about

defects such as long wavelength line edge roughness.

Figure 2: Top down SEM image (top left) of a photoresist

grating on a silicon wafer compared to the resulting 2-D

SAXS image (top right). Also shown are the intensities of

the diffraction peaks as a function of scattering vector,

q (=4π /λ sin θ, where λ is the x-ray wavelength) fit with

a simple model (solid blue line).

Figure 3: Schematic of via-pad patterns (a), where the blue

rectangles represent etched regions in a low-k film, and

(b) the resulting SAXS detector image.

In addition to precisely measuring dense patterns

of etched silicon oxide, the application of SAXS has

been demonstrated for a wide range of materials that

are currently used or are being explored for use in

the microelectronics industry. We demonstrated the

capabilities of SAXS on dense patterns of organic

photoresist, silicon oxide, and nanoporous low-k

samples (detector image from 2-D array of via pads

shown in Figure 3). Additionally, measurements on

samples of copper-filled, low-k patterns demonstrate

the capability to probe multiple component and metallic

patterns. Finally, the transmission geometry allows

the probing of densely packed structures, whether

buried or exposed, providing a potential to measure

other nanoscale 3-D structures being explored for

future microelectronic devices and photonic crystals.

Continuing efforts will focus on developing

quantitative measures of line edge and sidewall roughness,

isolating specific types of long-range order defects

arising from masks, and reconstructing an average 3-D

pattern shape. In addition, further investigations will

provide precise specifications for a laboratory scale

device capable of similar measurements.

For More Information on this Topic

R. Jones, T. Hu, W. Wu, E. Lin (Polymers Division,

NIST); G. Orji, T. Vorburger (Precision Engineering

Division, NIST); A. Mahorowala (T.J. Watson Research

Center, IBM); G. Barclay (Shipley Co.); D. Casa

(Advanced Photon Source, Argonne National Laborotory)

R.L. Jones, T.J. Hu, E.K. Lin, W.-L. Wu, D.M. Casa,

N.G. Orji, T.V. Vorburger, P.J. Bolton, G.G. Barclay,

Proc. SPIE 5038, 191 (2003).
12

High-throughput Measurements of Elastic Moduli of

Polymer Thin Films

As technology continues to strive towards smaller,

thinner, and lighter devices, more stringent demands

are being placed on polymer films as diffusion

barriers, dielectric coatings, electronic packaging,

etc. The material properties of thin films can be

drastically different from that of the bulk material.

Therefore, there is a growing need for testing

platforms that allow for rapid determination of the

mechanical properties of thin polymer films/coatings.

We demonstrate here a novel measurement technique

that yields the elastic modulus of supported

polymer films in a rapid and quantitative manner

without the need for expensive equipment or

material-specific modeling.

Christopher M. Stafford

There exist few techniques to measure the mechanical

 properties of polymer thin films (e.g., nanoindentation,

atomic force microscopy (AFM), surface acoustical wave

spectroscopy, and brillouin light scattering), each having

their own limitations and none of which are positioned to

be applied as high-throughput measurements. We present

a reliable, high-throughput technique by which the elastic

modulus of thin polymer films can be measured both

rapidly and quantitatively. Indeed, this technique is

very simple and practically any laboratory, academic or

industrial, can perform such measurements with only

modest investment in equipment.

This measurement platform exploits a classic

mechanical instability that occurs in laminates and

sandwich structures under compression. In this geometry,

a highly periodic buckling instability arises from a

mismatch of the elastic moduli of a relatively stiff polymer

coating that has been applied to a soft polydimethylsiloxane

(PDMS) substrate. The wavelength of the wrinkles

can be measured rapidly by conventional light scattering.

In addition, the sample can be rastered across the beam

to map out the properties of the entire film if the sample

is comprised of a gradient library, or if the sample is

uniform, a multitude of images can be acquired to generate

sufficient statistics. We have denoted this technique

as Strain Induced Elastomer Buckling Instability for

Mechanical Measurements (SIEBIMM). Since this is

an intrinsically local measurement, this technique is well

suited for measurements of combinatorial libraries with

spatially varying properties that can be prepared by existing

methodologies developed at NIST.

In general, thin polymer films are prepared on silicon

substrates either by flow coating or spin coating. The

thickness (h) of each film is measured extensively

by conventional interferometry. Films are transferred

to PDMS strips via aqueous immersion to produce a

laminate structure. Upon application of strain, the disparity

in the Poisson’s ratios (ν) between the PDMS substrate

and the polymer film results in a net compressive stress

on the glassy film perpendicular to the strain direction.

Conversely, higher degrees of compression can be obtained

by pre-stretching the PDMS prior to transfer of the

polymer film and then releasing the stressed PDMS/film

laminate. One mechanism by which the film can relieve

this applied stress is to buckle, thus producing a sinusoidal

phase grating whose periodicity or wavelength (d) can

be rapidly quantified by conventional light scattering.

The modulus of the upper film is calculated by the

following equation (as detailed by H.G. Allen, Analysis

and Design of Structural Sandwich Panels):

(1)

where Ep is the modulus of the upper film, and Em and

νm are the modulus and Poisson’s ratio of the PDMS

substrate, respectively. The Poisson’s ratio for PDMS

was measured to be 0.50 ± 0.05. In this formalism,

q =2π /d where d is the periodicity of the wrinkles. We

find that this equation is valid for Ep /Em > 20, which

allows a wide variety of materials to be measured.

Figure 1: (a) Optical image of a thickness gradient of

polystyrene, (b) optical images of the buckling pattern as a

function of film thickness, (c) light diffraction patterns from the

periodic wrinkles shown in (b).

Technical Highlights in Nanotechnology

> @> @    1 3 12 3 1   E E   qh p m Q m Q m
13

Initial validation of this concept focused on a

thickness gradient of polystyrene ranging from 140 nm

to 280 nm in thickness. According to Equation 1, the

buckling wavelength should be inversely proportional to

the thickness of the upper film for a film of constant

modulus, Ep. Figure 1 demonstrates the validity of

Equation 1: as the film thickness increases by a factor of

two, the buckling wavelength also increases by a factor

of two as measured by both optical microscopy and light

scattering. Through Equation 1, the modulus of the

polystyrene film is calculated to be 3.17 GPa ± 0.11 GPa

for the entire range of thickness. These values are in

excellent agreement with the measured bulk value of

3.22 GPa ± 0.05 GPa for the same polymer.

the light scattering experiment due to the small domain

sizes. The results of this experiment can be seen in

Figure 3 where thin film data are shown in blue and

bulk tensile tests are shown in red. While the bulk

tests suffer from a great deal of scatter, perhaps due to

variations in sample preparation and handling, buckling

measurements show a comparatively smooth increase

in modulus with increasing PS fraction. As shown in

Figures 2 and 3, the moduli range accessible by this

method is as low as 5 MPa and as high as several GPa.

Figure 2: Modulus of polystyrene thin films as a function of mass

fraction of added plasticizer, dioctyl phthalate.

This method was also applied to a model system

that varied in mechanical properties. Here, a common

plasticizer (dioctyl phthalate) was solution blended

with polystyrene prior to spin coating. As shown

in Figure 2, the measured modulus (blue) of the

polystyrene film decreases in a sigmoidal manner

with increasing concentration of added plasticizer.

These results were compared against nanoindentation

data (red) obtained on identical films supported on

silicon wafers. The agreement between the buckling

method and nanoindentation is markedly good.

Measurements were also performed on blends

of polystyrene-polyisoprene-polystyrene (P(S-I-S))

triblock copolymers to demostrate the applicability to

soft, structured materials. Two commercially available

copolymers of P(S-I-S) with different fractions of the

glassy component (PS) were solution blended prior

to spin-coating into micron thick films. Since the

periodicity of block copolymer microdomains is on

the order of 30 nm, thick films should exhibit bulk-like

mechanical behavior. Also, the microphase-separated

structure of the copolymer should not interfere with

We have developed a novel, high-throughput technique

that allows the elastic modulus of polymer thin films to

be determined rapidly and quantitatively. The SIEBIMM

technique exploits a strain-induced buckling instability

in elastomer-supported films that exhibits a modulus

dependent wavelength. Conventional light scattering

can quickly access the wavelength of the wrinkles,

and the modulus can be calculated using a simple model.

We measured films with thicknesses ranging from several

micrometers to 20 nm and films with a range of moduli

from several GPa to 5 MPa.

Research is continuing in the areas of nanoporous

low-k films, metal and ceramic thin films, and

UV-curable materials. In addition, the method shows

promise for the study of such issues as aging effects,

creep, stress-relaxation, and viscoelasticity. There is

also interest in exploiting these sinusoidal surfaces as

tunable phase gratings and using these tunable textured

surfaces to examine a number of scientific problems,

such as patterned cell growth and anisotropic adhesion.

For More Information on this Topic

C.M. Stafford, A. Karim, E.J. Amis (Polymers Division,

NIST), C. Harrison (Schlumberger–Doll Research)

Figure 3: Modulus of P(S-I-S) triblock copolymer blends with an

increasing glassy component, PS.

Technical Highlights in Nanotechnology
14

Elastic Flow Instability in Polymer-Dispersed Carbon Nanotubes

Novel composites engineered from polymers

and carbon nanotubes offer the promise of

plastics with enhanced thermal, electronic, and

mechanical properties, but the ability to control

and quantify particle dispersion in such materials

is an unresolved issue of fundamental importance.

Of particular interest is how processing flows

influence tube dispersion and orientation.

We are developing metrologies and methods that

directly address the fundamental nature of elastic

flow instabilities in polymer-dispersed carbon

nanotubes, enabling better control of dispersion

during flow processing of melts and suspensions.

Erik K. Hobbie

The clustering of small spherical particles has been

 studied extensively in a broad range of systems.

In contrast, relatively little is known about the

flocculation of asymmetrical particles, such as

platelets, rods, or fibers. Given the current interest in

dispersing anisotropic nanoparticles in organic materials

to enhance physical properties, a deeper understanding

seems warranted. An almost universal aspect of

aggregation is inter-particle attraction, but external

hydrodynamic forces, often used to disperse such

particles, can alone induce clustering in highly

anisotropic suspensions, creating unique challenges and

issues relating to the flow processing of such materials.

We recently observed an elastic instability associated

with flow-induced clustering in polymer dispersed

carbon nanotubes. Kinetic measurements under varied

confinements and shear stresses were compared with

simulations of flocculation in flowing fiber suspensions,

and we found an intriguing rheological signature consistent

with highly elastic domains. Small-amplitude oscillatory

shear measurements reveal this extraordinary elasticity,

with homogenized semi-dilute suspensions showing

gel-like behavior at long time scales. The data suggest

that the underlying instability may in fact be universal

to a number of flowing complex fluids, with important

implications for the flow processing of polymer-carbon

nanotube composites.

Multi-walled carbon nanotubes (MWNTs) were

grown via chemical vapor deposition. A typical electron

micrograph is shown in the inset to Figure 1(a). Based

on such measurements, the mean diameter is d ≈ 50 nm.

Due to their length and optical contrast, individual

MWNTs are discernable in optical micrographs of 25x

or higher, and from 200x images of thin-film dispersions,

the mean length is L ≈ 12 μm. The suspending

polyisobutylene fluid (PIB) is Newtonian over a broad

range of shear rates, with a shear viscosity of 10 Pa-s

at 25 oC. Dispersions are prepared by dissolving the

PIB in sonicated MWNT-toluene suspensions, which

are stirred continuously as the solvent is removed.

Suspensions of primary interest contain 1.7 x 10–3

mass-fraction MWNT in PIB and are semi-dilute,

with nL3 ≈ 45 and nL2d ≈ 0.19, where n is the

number of tubes per unit volume. The tubes in PIB

are non-sedimenting over the time scales in question.

Figure 1: (a) Optical micrograph of MWNTs in a quiescent PIB

dispersion. The inset (width = 1.3 μm) is a SEM image of the

MWNTs before dispersion in PIB. (b) Optical micrograph 30 min

after quenching the mixture to a shear rate of γo = 0.03 s–1.

The flow (x) direction is horizontal. (c) Optical micrograph 2 h

after the quench. (d) Optical micrograph 15 min after quenching

the sample in (c) to γm= 10 s–1.

.

.

Technical Highlights in Nanotechnology

Optical microscopy (5x to 25x) is used to observe

the motion of MWNTs and the formation of aggregates

under shear, with flow along the x-axis, a constant

velocity gradient along the y-axis, and vorticity along the

z-axis. Measurements are taken in the x-z plane. The

sample is confined between two parallel quartz plates

separated by a variable gap, h. The upper plate rotates

at an angular speed that sets the shear rate, γ = ∂νx /∂y,

at a fixed point of observation in the middle of the

plates. A controlled-strain rheometer in cone-and-plate

and parallel-plate configurations provides steady

and oscillatory shear measurements of the rheology.

All measurements were performed at 25 oC.

The aggregates have “melted” and the redispersed

tubes broadly orient with the direction of flow, as

evident in the light-scattering pattern (inset Figure 1(d),

scale bar = 1 μm–1). The scale bar is 10 μm and the

gap (h) is 70 μm.

.
15

Figure 2: Evolution of a confined dispersion (upper), where

the micrographs have been converted to binary images.

The lower images are the corresponding c(r). The flow direction

is horizontal, the vorticity axis is vertical, and the red scale bar

(125 μm) applies to all six images. As in Figure 2, h = 70 μm.

The inset to the lower left image is its FFT (width = 1.2 μm–1),

which gives the ubiquitous “butterfly” pattern.

coefficient of friction. Our measurements are in

agreement with simulation. With an elastic bending

modulus 103 times larger than that of a typical fiber,

the MWNTs are flexible enough to exhibit shape

deformation, yet they readily entangle and interlock to

form large coherent structures under weak shear. Held

together by elastic forces, the diffuse clusters store

sizeable energy, which we infer from linear viscoelastic

measurements of the storage modulus, G′(ω), as a

function of n. Other unusual features, such as a

negative first normal stress difference, are currently

under in-depth investigation.

We have observed the early-time domain pattern

[Figure 2 (left), weak minima in c(x)] in a host of

flowing complex fluids, including polymer blends,

semi-dilute polymer solutions, physical polymer–clay

gels, and thixotropic clay gels, all of which fall within

the simple paradigm of weakly interacting elastic

domains suspended in a less viscous fluid. The

homogenized semi-dilute dispersions also exhibit

solid-like behavior at long timescales, suggesting

the presence of a weak “network” or gel, further

reminiscent of other systems that exhibit this type

of flow-induced macrostructure. The role of

confinement in the growth of periodic structures

in these systems is intriguing and merits detailed

computational consideration. We expect that

these issues will have direct consequences for

the processing of nanocomposite melts, and we

are currently extending these measurements to

single-walled carbon nanotubes.

For More Information on this Topic

E.K. Hobbie, S. Lin–Gibson, J. Pathak (Polymers

Division, NIST); H. Wang (Michigan Tech); E. Grulke

(University of Kentucky)

Figure 3: The measured late-t “pattern diagram” in the h – γ

plane for the semi-dilute, non-Brownian MWNT-PIB suspensions

of interest, with homogeneous (H), aggregated (A), and

“striped” (S) regions as indicated.

.

Technical Highlights in Nanotechnology

Under weak shear, the tubes form macroscopic

domains consisting of diffuse MWNT networks.

Figure 1 shows optical micrographs of (a) a quiescent

dispersion, (b & c) aggregation at γo = 0.03 s–1,

and (d) redispersed MWNTs after dissolution at

γm = 10 s–1, where light scattering reveals a

steady-state distribution of orientations broadly peaked

around x. In simple shear, the long axis of an isolated

rod rotates around z with a period, τ, that scales as γ –1.

In semi-dilute suspensions, hydrodynamic interactions

determine the distribution of such orbits. The Peclet

number is less than 10–4, implying that hydrodynamic

forces overwhelm Brownian forces.

.

.

8

8 .

By varying h, we observe the transition from bulk

to confined growth. To quantify the latter, we convert

micrographs into binary images in which the clusters

are black and the surrounding fluid white (upper images,

Figure 2), defining a coarse composition field ψ(r).

Ensembles at each annealing time, t, are used

to compute the two-point correlation function,

c(r) = 〈ψ(r)ψ(0)〉 (lower images, Figure 2), and

the steady-state morphology diagram in the h – γ plane

is shown in Figure 3. In region A, moderate aspect

ratio domains exhibit broad vorticity alignment. 

In region S, these domains coarsen along z into

macroscopic striped patterns. The dashed curve

marks a region of “metastability” in which the striped

pattern is transient.

Recent simulations of flow-induced flocculation

in non-Brownian fiber suspensions suggest that interparticle friction leads to aggregation in the absence of

attractive interactions, particularly at low-shear stress

and high-fiber stiffness. The MWNT bending modulus

can be compared with values for typical organic fibers,

as can the shape of the inter-particle potential and

.

8
16

Technical Highlights in Health Care

Non-destructive, in vitro evaluation of tissue

engineered medical products (TEMPs) will shorten

their development time. Imaging techniques such

as collinear optical coherence and confocal

fluorescence microscopies are being used to

address the challenges of imaging these systems.

An equally important component of the work is

the image quantification as a vehicle to evaluate

the voluminous imaging data.

Joy P. Dunkers and Marcus T. Cicerone

Tissue engineered medical products (TEMPs) are

often three-dimensional (3D) hybrid materials

consisting of a porous scaffold upon which the tissue is

grown. While it is generally understood that a complex

interaction of many variables influences the success of

the TEMPs, the precise nature of these interactions has

yet to be worked out in many instances. A significant

difficulty in furthering the understanding of the

interaction between these factors and cell behavior is

the lack of a high-resolution imaging technique that can

penetrate deeply and non-destructively into the scaffold.

We have developed an approach that uses advanced

optical imaging to non-invasively monitor the developing

tissue. However, before any assessment of the tissue

viability can be made, the volumes of imaging data

must be rigorously analyzed. Therefore, an equally

important component of this effort is image

visualization and quantification. Progress in these

areas is summarized below.

Multi-Modal Imaging

We have constructed an instrument that can

gather information on a TEMP using multiple imaging

modalities. This means that each channel of imaging

data provides different but complimentary information.

Optical coherence microscopy (OCM) was chosen

as the technique to image scaffold, cell, and tissue

structure because of its unique combination of high

resolution (≈ 1 μm) and high sensitivity (> 100 dB).

OCM is an interferometric technique that uses both

confocal and coherence gating mechanisms for stray

light rejection, rendering it comparable in resolution to

laser scanning confocal microscopy but far superior in

imaging depth. We have added confocal fluorescence

microscopy (CFM) to the OCM to collect information

on cell function using traditional cell staining

techniques. In our collinear instrument, we collect

volumetric images of cell and scaffold structure using

the OCM channel and cell function using the CFM

channel. Each channel is then overlayed in the rendered

image for maximal insight.

Scaffold Structure and Cell Function through Multi-Modal Imaging

and Quantitative Visualization

Figure 1: Image of merged and registered OCM and CFM

images of the cultured PCL scaffold at 145 μm below the surface.

Figure 1 displays merged and registered OCM and

CFM images 145 μm below the surface of a TEMP.

The TEMP consists of a volume fraction of 50 %

poly(ε-caprolactone) (PCL) scaffold that was cultured

with fetal chick osteoblasts for 10 weeks and stained

with a nuclear stain. In Figure 1, the regions of low

OCM signal are red (pores), high OCM signal are black

(scaffold), and regions of high CFM signal are yellow

(cells). CFM complements OCM by allowing us to

positively identify stained tissues at more shallow

depths. Once identified, OCM allows us to discriminate

these tissues from scaffold and, thus, view them

at a greater depth. This will form the basis of

structure–property relationships for TEMPs based

on microscopic characterization of scaffold properties

and concomitant cellular responses.

Quantitative Visualization

Quantification of scaffold properties must be

performed to establish scaffold structure and cell

function relationships and to optimize scaffold design.

One of our goals is to design an approach that is valid

with any pore structure. Figure 2 displays a volumetric

view of the PCL scaffold images collected using x-ray

computed tomography. In this figure, the pores are

colored in red and the scaffold in green. From viewing

this image, one gets a qualitative sense of the need for

such an approach. Heterogeneity in the microstructure

is exhibited by the difference in pore size, shape, and

anisotropy as seen on the different faces of the volume.

Pore volume, size distribution, tortuosity, and

connectivity are metrics of interest for the scaffold

microstructure.
17

Technical Highlights in Health Care

An example of the type of information gleaned from

the imaging data is shown below. Figure 3 displays the

pore size as measured by the chord length distribution

function (CLDF). The CLDF is the probability of

finding a chord of length l between x and x + dx entirely

in one phase. Chords are defined as the segments

formed by the intersection of lines with the interface

between two phases.

on real material images. This relationship, plus the

analysis of the structural problem of interest, provides

a means of optimizing the performance of TEMPs

by varying individual constituent properties without

conducting a variety of time-consuming experiments.

Initially, the properties of interest are anisotropic elastic

constants. Figure 4 displays a typical mesh of FEA

based on a section of the PCL scaffold from Figure 2.

Figure 2: X-ray computed tomographic reconstruction of a

PCL based scaffold. Dimensions: 1.0 mm on each side.

Figure 3: Example of a CLDF from one image plane in Figure 2.

Another important aspect of the effort to optimize

scaffold design is the need to balance competing

requirements. High porosity is required because of

the need for cell migration, proliferation, and nutrient

influx. However, the drive towards higher and higher

pore volumes opposes the need for certain mechanical

property requirements, especially in orthopedic

applications. To this end, we are using 3D finite

element analysis (FEA) to develop an analytical tool to

predict the relationship between the effective properties

and individual constituent properties of TEMPs based

Figure 4: Finite element mesh of a subsection of scaffold shown

in Figure 2. The dimension is 274 μm on each side.

This work represents a systematic, integrated

approach to the study of structure/function

relationships and optimal design in TEMPs. We will

be able to extract metrics for the anisotropic scaffold

microstructure and properties and use that information

to understand their influence on cell function, and, on a

larger scale, TEMP viability.

For More Information on this Topic

F. Landis, M. Chiang (Polymers Division, NIST)

M.T. Cicerone, J.P. Dunkers, and N.R. Washburn,

“Towards in-situ Monitoring of Cell Growth in

Tissue Engineering Scaffolds: High Resolution Optical

Techniques,” Tissue Engineered Medical Products

(TEMPs) ASTM STP, 1452, November 3, 2002,

Miami Beach, FL.

For information involving chemical imaging of

TEMPs, see the project page entitled “Coherent AntiStokes Raman Micro-spectroscopy (μ-CARS) for

Understanding Tissue Growth in Scaffold Constructs”

by M. Cicerone and T. Kee.
18

Macromolecular Dynamics via Inelastic Neutron Scattering

The impact of this work is clear. The resist

community was not aware that diffusive properties

could change with film thickness. Dr. Robert Brainard

of the Shipley Corporation comments, “I really think

this work is an eye opener.” We also have evidence

indicating that this reduced diffusivity in thin-resist

films also leads to slower dissolution rate in the

aqueous base developer.

Switching to preservation, proteins are often

lyophilized (freeze-dried) from viscous sugar solutions

to stabilize biochemical functionality. The first

requirement of a preservation media is that it does not

denature the protein due to thermodynamic interactions.

Screening materials for this incompatibility is fast and

easy. The difficulty comes when one must predict

which of the thermodynamically compatible glasses will

be the most effective preservation media. This requires

tedious long-term stability studies, which rely upon trial

and error. Dr. Robert Langer, Chair of the FDA’s

Science Committee, identified the need to develop

protein stabilization technologies as one of the most

pressing problems facing pharmaceutical and

biomaterials sectors.

Figure 1: Reduced mobility/diffusivity as a function of PBOCSt

film thickness directly reflected by H+ (circles) and H2O (squares)

motions and predicted by <u2> (stars & dotted line).

Technical Highlights in Health Care

Neutron scattering has been an invaluable tool

for the advancement of basic polymer science.

At NIST, we are uniquely situated to leverage the

world-class inelastic neutron scattering facilities

being developed at the NIST Center for Neutron

Research (NCNR). Our mission is to develop

fundamental measurements and uses of these

resources in a manner that enables critical

and emerging technologies.

Christopher L. Soles

We illustrate two examples where fundamental

studies of macromolecular dynamics, via

neutron scattering, have spawned metrologies that are

critical for an emerging technology. These include the

impact of thin-film dynamics on chemically amplified

photoresists and protein preservation. In each instance,

the insight from neutron scattering has provided

invaluable insight into an industrially relevant and

difficult problem.

The semiconductor industry is faced with a

relentless drive to produce devices with smaller

dimensions. This dictates that lithographers use

increasingly thinner photoresist films, soon to be less

than 100 nm thick. This is of concern since properties

can deviate when polymer films approach these

dimensions. Industrial partners indicate that resist

performance typically deteriorates in films less than

100 nm thick. Detailed concerns focus on dynamics

because the resolution of a chemically amplified

photoresist requires a delicate balance of photoacid (H+)

reaction and diffusion; it is reasonable to anticipate that

diffusion is coupled to the dynamics in the film.

To directly probe the dynamics of thin polymer

films, we designed incoherent neutron scattering

measurements utilizing the NCNR’s High Flux

Backscattering Spectrometer (HFBS), which

characterizes atomic vibrations and relaxations on time

scales ≥ 200 MHz (faster than a few nanoseconds) in

terms of a Debye–Waller factor and the mean-square

atomic displacement <u2>. In several publications,[1]

we observe a strong suppression of <u2> with

decreasing thickness, even in films as thin as 75 Å.

To determine if reduced polymer mobility is germane

to the observed deviations in thin film lithography, the

diffusion and reaction of H+ into a photoresist polymer

(PBOCSt) was studied through a series of bilayer

diffusion couples.[2] This revealed a strong decrease

of the effective reaction-diffusion coefficient when the

films were less than 100 nm. HFBS measurements on

these PBOCSt films confirm a suppression of <u2>

at a similar film thickness.[3] We then use a relation

between <u2> and diffusivity and predict the film

thickness at which the H+ reaction-diffusion kinetics

diverge.[3] Figure 1 displays this correlation in

conjunction with moisture diffusion coefficients

obtained with a quartz crystal microbalance.[4] That

the diffusivity of a non-reactive water molecule tracks

the H+ reaction-diffusion suggests that deviations with

PBOCSt film thickness reflect changes in the transport

properties, not the chemical kinetics.
19

We demonstrate, by coupling HFBS[5] and protein

activity measurements,[6] that <u2> indicates the efficacy

of a glass at stabilizing a protein. Figure 2 shows the

thermal evolution of <u2> in a series of trehalose glasses

diluted with mass fractions of glycerol (φglycerol) at

0, 0.05, 0.10, 0.15, and 0.20. Increasing φglycerol

monotonically decreases the calorimetric glass transition

temperature Tg, indicated by the upturn of <u2>.

However, a maximum suppression of <u2> occurs

at φglycerol = 0.05, indicating that small amounts of

glycerol are best for suppressing the atomic fluctuations

in trehalose. This suppression of <u2> is quantified

between (40 and 200) K in terms of a harmonic

oscillator. The elastic spring constant k (inset Figure 2)

of these vibrations shows a pronounced maximum at

φglycerol = 0.05.

Figure 2 (inset) also displays the deactivation

lifetimes (τ) for horseradish peroxidase lyophilized in

these trehalose mixtures. An order of magnitude

increase in protein stabilization at φglycerol = 0.05

coincides with the peak in k. While the data are not

shown, the same trend is seen with the protein alchohol

dehyrodgenase. In short, a strong suppression of <u2>

indicates a highly effective preservation media. This

insight from neutron scattering enables a powerful

metrology for screening candidate materials. To further

promote this tool, we are simultaneously developing

Raman scattering (optical) methodologies that provide

comparable information without the need of a nuclear

reactor.[7]

It is not surprising that suppressing the nanosecond

atomic fluctuations leads to enhanced stability. These

local motions are necessary precursors for the global

conformational fluctuations in a protein that occur on

the physiological time and length scales. Suppressing

Figure 2: The T dependence of <u2> with glycerol content.

The inset correlates the vibrational spring constant k between

(40 and 200) K with the protein lifetimes τ; both k and the

degree of protein stability show a pronounced maximum at

φglycerol = 0.05.

Technical Highlights in Health Care

<u2> makes protein unfolding or denaturation more

difficult. Likewise, deactivation can also be induced by

the diffusion of reactive gases into the protein through

the glassy matrix. Figure 1 clearly illustrates that

suppressing <u2> retards diffusion.

Molecular insight into the suppression of <u2>

can be inferred by positron annihilation lifetime

spectroscopy, which quantifies unoccupied volume

at the interatomic or nanometer length scales.

Glasses with open structures at these levels also

display enhanced dynamical fluctuations[8] (evidenced

via <u2>) and softened collected atomic vibrations.[9]

This suggests that a small amount of glycerol

(or thin-film confinement in Figure 1) enhances

intermolecular packing. This stiffening or “caging”

decreases the success rate for vibrations turning into

relaxations. It is these relaxations that lead to diffusion

or protein deactivation.

References

1. C. Soles, J. Douglas, W. Wu, Phys. Rev. Lett. 88,

037401 (2002); ibid, Macromolecules 36, 373 (2003);

C. Soles, E. Lin, J. Lenhart, R. Jones, W. Wu,

D. Goldfarb, M. Angelopoulos, J. Vac. Sci. Technol.

B 19, 2690 (2001).

2. D. Goldfarb, M. Angelopolous, E. Lin, R. Jones,

C. Soles, J. Lenhart, W. Wu, J. Vac. Sci. Technol. B

19, 2699 (2001).

3. C. Soles, J. Douglas, E. Lin, J. Lenhart, R. Jones,

W. Wu, D. Goldfarb, M. Angelopolous, J. Appl.

Phys. 93, 1978 (2003).

4. C. Soles, R. Jones, J. Lenhart, V. Prabhu, W. Wu,

E. Lin, D. Goldfarb, M. Angelopolous, Proc. SPIE

5039, 336 (2003).

5. M. Cicerone and C. Soles, Biophys. J. (2003)

(submitted).

6. M. Cicerone, A. Tellington, L. Trost, A. Sokolov,

Bioprocess Intl. 1, 23 (2003).

7. G. Caliskan, A. Kisliuk, A. Tsai, C. Soles, A. Sokolov,

J. Chem. Phys. 118 (2003); 4230; ibid, J. Non-Cryst.

Solids 307–310, 887 (2002).

8. K. Ngai, L. Bao, A. Yee, C. Soles, Phys. Rev. Lett.

87, 215901 (2001).

9. C. Soles, R. Dimeo, D. Neumann, A. Kisliuk,

A. Sokolov, J. Liu, A. Yee, W. Wu, Macromolecules

34, 4082 (2001).

For More Information on this Topic

W. Wu, M. Cicerone, J. Douglas (Polymers Division,

NIST); D. Neumann (NCNR, NIST); A. Sokolov

(U. Akron); A. Tsai (Human Genome Services)
20
21

Program Overview

Advanced Manufacturing Methods

The industrial competitiveness of U.S. manufacturers

depends on their ability to reduce the time from product

concept to market while decreasing product cost. This

is as true for well-established “commodity” industries,

such as automotive and aerospace, as it is for rapidly

growing or emerging industries, such as biotechnology

and nanotechnology. Manufacturing is a critical step

in realizing such reductions in product cycle time:

for many industries and products, the rapid, low-cost

development of manufacturing processes is needed

to create new materials with complex product shapes

and higher performance at the same or lower cost as

the competing, older materials and methods.

To realize such improvements in manufacturing,

MSEL is working to develop robust measurement

methods, standards, and materials and process data

that will help in the design, monitoring, and control

of manufacturing processes. An increasingly

important step in manufacturing is process modeling.

Development of optimized manufacturing processes,

such as stamping of complex auto panels or machining

of large aircraft components, is time consuming and

labor intensive. In many cases, the resulting processes

are far from optimal because materials variability, caused,

for example, by residual stresses or strain localization

during processing, leads to lower yields. Our approach

is to develop and combine higher precision, spatially

localized measurement methods with realistic,

physics-based modeling of manufacturing processes

and materials process data to create more useful

process modeling tools.

Depending on the stage of the research, our

research is often conducted in close collaboration

with industrial consortia and standards organizations.

This close working relationship developed through

these organizations not only ensures the relevance of

our research, but also promotes rapid transfer of our

research to industry for implementation.

The performance of metallic components in products

is strongly dependent on processing conditions that

determine microstructural features, such as grain size

and shape, texture, the distribution of crystalline phases,

macro- and microsegregation, and defect structure

and distribution. NIST expertise is applied from a

wide range of disciplines, including thermodynamics,

electrochemistry, fluid mechanics, diffusion, x-ray,

and thermal analysis, to develop measurement methods

and understand the influence of processing steps

for industries as diverse as automotive, aerospace,

microelectronics, and defense. Two major MSEL efforts

in Polymer Processing and Forming of Lightweight

Metals are centered on unique measurement facilities.

Rapidly growing and emerging industries such as

biotechnology and nanotechnology are also dependent

upon the development of new advanced manufacturing

methods that can produce metallic components with

the desired characteristics and performance. Related

projects with significant manufacturing processes

components can be found in the MSEL Programs

on Nanocharacterization, Materials for Micro- and

Opto-Electronics, and the Interface of Materials

with Biology.

Forming of Lightweight Metals

Automobile manufacturing is a materials

intensive industry that involves about 10 % of the U.S.

workforce. In spite of the use of the most advanced,

cost-effective technologies, this globally competitive

industry still has productivity issues related to

measurement science and data. Chief among these

is the difficulty encountered in die manufacture for

sheet metal forming. In the ATP-sponsored workshop

(The Road Ahead, June 20–22, 2000), the main

obstacle to reducing the time between accepting a new

design and actual production of parts was identified

as producing working die sets. To benefit from the

weight saving of high strength steel and aluminum

alloys, a whole new level of formability measurement

methods and data is needed, together with a better

understanding of the physics behind metal deformation.

MSEL is working to fill this need.

Polymers Processing

Polymers have become ubiquitous in the modern

economy because of their ease of processing, high

functionality, and low cost. However, these materials

can exhibit complex and sometimes catastrophic

responses to the forces imposed during manufacturing,

thereby limiting processing rates and the ability to

predict ultimate properties. The focus of our polymer

research is on microscale processing, modeling of

processing instabilities, and on-line process monitoring

of polymers. Our unique extrusion visualization facility

combines in-line microscopy and light scattering for the

study of polymer blends, extrusion instabilities, and the

action of additives. Current applications focus on

understanding and controlling the “sharkskin instability”

in polymer extrusion and observation of the dielectric

properties of polymer nanocomposites. 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.

Contact: Carol A. Handwerker
22

Advanced Manufacturing Methods

Processing Flows & Instabilities

The goal of this project is to develop and utilize

advanced in situ measurement tools to enable

the understanding and control of the complex

flows that occur during polymer processing.

Systems for study are chosen when the in situ

measurements can resolve outstanding scientific

and engineering questions. Particular emphasis

is on tools to quantify instabilities, interfacial,

and multi-component flows.

Kalman B. Migler

I

n the extrusion of linear low-density polyethylene

 (PE), fluoropolymer-processing additives (PPA)

are used to eliminate the surface defect known as

“sharkskin.” Added to the PE at approximately 0.1 %

mass fraction, they coat the internal wall of the die

during extrusion and provide a slippery surface for the

polyethylene, which then slides through undistorted,

while reducing energy consumption due to decreased

friction.

 However, the ability to develop next generation

fluoropolymer additives is hampered by a lack of

understanding of how they work. In particular, the

manner in which they coat the die is not understood;

in fact, according to standard fluid mechanics, the

fluoropolymer droplets should be repelled by the walls

during extrusion.

Working with PPA manufacturers, we have

been examining the question of why and where the

fluoropolymers coat the die, as well as working to

quantitate their behavior once they get there. Past

work revealed the details of the sharkskin kinetics and

precisely why the fluoropolymers cause the elimination

of sharkskin. We showed that the PPA coating is not

uniform, but, rather, it forms streaks on the die wall.

We recently developed an in situ measurement tool

based on frustrated total internal reflection (Frus-TIR)

optics. With this technique, we can monitor the coating

kinetics in real-time and correlate it with the reductions

in sharkskin and energy consumption.

We find that, first, the fluoropolymer coats the

upstream region; then, it migrates down the wall to

the exit region. When the coating in the exit region is

sufficiently established, then sharkskin is eliminated.

We have determined that the coating occurs in the

upstream region of the die and that the typical steady

state coating thickness ranges from 200 nm to 500 nm,

depending on the extrusion conditions and additive

concentrations. However, a coating thickness of less

than 60 nm can also eliminate sharkskin.

Figure 1: Sketch of the coating process of a fluoropolymer additive

onto a solid substrate during the extrusion of polyethylene.

Figure 2: Frustrated Total Internal Reflection optics is installed

near the die exit on a capillary rheometer. The amplitude of the

reflected light allows a determination of the coating thickness.

 We have developed a model of the coating process

based on a steady state mass balance equation. This

model predicts reasonably well the thickness of the

coating. It also gives new insight into the role of the

experimental variables on the coating process. For

example, we can now make predictions on the effects

of throughput, viscosity, entrance angle, and droplet

size; these will be explored in future work.

Contributors and Collaborators

S. Kharchenko, P. McGuiggan (Polymers Division,

NIST); M. Meillon, D. Morgan, D. Bigio (University

of Maryland); C. Macosko (University of Minnesota);

S. Oriani (DuPont Dow Elastomers)
23

Program Overview

Combinatorial Methods

and online at www.nist.gov/combi. Within the

Materials Science and Engineering Laboratory (MSEL),

novel methods for combinatorial library preparation are

designed to encompass variations of diverse physical

and chemical properties, such as composition, film

thickness, processing temperature, surface energy,

chemical functionality, UV-exposure, and topographic

patterning of organic and inorganic materials ranging

from polymers to nanocomposites to ceramics to

metals. New instrumentation and techniques have

been developed that enable the high-throughput

measurements of adhesion, mechanical properties,

failure mechanisms, film thicknesses, and refractive

index, among others. The combinatorial effort

extends to multiphase, electronic, optoelectronic,

and magnetic materials, including biomaterials

assays. On-line data analysis tools, process control

methodology, and data archival methods are also

being developed as part of the Program’s

informatics effort.

The extensive outreach activity in the Combinatorial

Methods Program is designed to facilitate technology

transfer with institutions interested in acquiring

combinatorial capabilities. The centerpiece of this effort

is the NIST Combinatorial Methods Center (NCMC),

an industry–university–government consortium organized

by MSEL that became operational on January 23, 2002

via a kick-off meeting in San Diego. The recognized

importance of NCMC activities is readily apparent, as

15 industrial partners, the Air Force Research Lab, and

the University of Southern Mississippi are participating

in the NCMC membership program. The membership

continues to grow and 80 % of the members from last

fiscal year have already renewed for this fiscal year.

The NCMC facilitates direct interaction between NIST

staff and these industrial partners, and it provides a

conduit by which Combinatorial Methods Program

research products, best practices and protocols,

instrument schematics and specifications, and other

combinatorial-related information can be effectively

disseminated. This outreach is mediated in large

part by a series of semi-annual workshops for

NCMC members. Indeed, since its inception,

four NCMC workshops have been held at NIST.

Further information on the NCMC can be found

on the website at www.nist.gov/combi.

Contact: Alamgir Karim

The Combinatorial Methods Program develops

novel high-throughput measurement techniques and

combinatorial experimental strategies specifically

geared towards materials research. These tools

enable the industrial and research communities to

rapidly acquire and analyze physical and chemical data,

thereby accelerating the pace of materials discovery

and knowledge generation. By providing measurement

infrastructure, standards, and protocols, and by

expanding existing capabilities relevant to combinatorial

approaches, the Combinatorial Methods Program

lowers barriers to the widespread industrial

implementation of this new R&D paradigm.

The Combinatorial Methods Program has adopted a

two-pronged strategy for accelerating the development

and implementation of combinatorial approaches:

an active intramural R&D program and an ambitious

outreach activity. The intramural R&D program is

designed to better tailor combinatorial methods for the

materials sciences and extend the state-of-the-art in

combinatorial techniques. Measurement tools and

techniques are developed to prepare and characterize

combinatorial materials libraries, often by utilizing

miniaturization, parallel experimentation, and a high

degree of automation. A key concern in this effort is

the validation of these new approaches with respect

to traditional “one at a time” experimental strategies.

Accordingly, demonstrations of the applicability of

combinatorial methods to materials research problems

provide the scientific credibility needed to engender

wider acceptance of these techniques in the industrial

and academic sectors. The successful adoption of the

combinatorial approach also requires a highly developed

“workflow” scheme. All aspects of combinatorial

research, from sample “library” design and library

preparation to high-throughput assay and analysis,

must be integrated through an informatics framework,

which enables iterative refinement of measurements and

experimental aims. Combinatorial Methods Program

research projects give illustrations of how combinatorial

methodology is implemented effectively in a research

setting.

NIST-wide research collaborations, facilitated by

the Combinatorial Methods Program, have produced

a wide range of new proficiencies in combinatorial

techniques, which are detailed in a brochure,

“Combinatorial Methods at NIST” (NISTIR 6730),
24

Combinatorial Methods

Polymer Formulations: Fluidic Devices and Scattering

Measurements for High Throughput Materials Research

To meet an increasing demand for combinatorial

approaches to polymer formulations science, we are

developing fluid handling and measurement methods

to extend combinatorial and high-throughput

(C&HT) materials science to complex fluids. Two

examples are highlighted here. Solvent resistant fluid

handling devices with channels of tunable dimensions

are fabricated within a few hours using a novel

rapid prototyping technique, and a complimentary

approach to measure formulation microstructure on

arrays of mixtures is developed using x-ray scattering.

Kathryn Beers

As gauged by the response of NIST Combinatorial

 Methods Center (NCMC) members, one of the

greatest opportunities for contribution of combinatorial

methods is in the area of complex fluid formulation.

The ability to manipulate and measure multi-component

mixtures with C&HT methods is attracting considerable

industrial and academic interest.

We have developed a rapid prototyping technique able

to produce solvent-resistant fluidic devices.[1] It is based

on the contact lithography of a UV curable optical adhesive

and requires only a mask (a laser printed transparency or

image setter) and a conventional 365 nm UV source. Fluid

handling devices with channels of tunable dimensions

(of the order of 100 s of μm) are fabricated within a

few hours.

and substrates for discrete composition libraries. With

these library substrates, a home-built liquid dispenser, and

automated light scattering, we are investigating the phase

behavior of multi-component polymer formulations.

Through the development of this fabrication technique,

a complimentary approach to measure scattering from

a discrete composition library was also demonstrated.

The substrate, a polydimethylsiloxane (PDMS) array,

was capped with polyimide windows. The library was

investigated by Small Angle X-Ray Scattering (SAXS)

at the National Synchrotron Light Source at Brookhaven

National Laboratory. This model library contained

compositions of aqueous ethyleneoxide (EO)

butyleneoxide (BO) block copolymer, EO6BO11,

which is known to produce vesicle structures at low

concentration.[4] The vesicles are micrometers in size,

which makes this system an excellent model to be

used in developing additional C&HT techniques using

a variety of in-house scattering systems.

Figure 1: Height of patterned structures as a function of

administered UV dose; symbols are experimental data and the

solid line is a logarithmic fit.[2] The inset shows a patterned

resolution target (USAF 1951) reproducing linewidths

(in-plane dimensions) of 70 μm and above.

Figure 2: I(q) vs. q vs. concentration for the SAXS data from

EO6BO11 in water. Evolution of lamellar structure within

the vesicle and the absence of crystallinity are both evident.

The inset shows the PDMS/polyimide array.

Future work includes developing a suite of

processing capabilities using the prototyping technique

and interfacing the formulations libraries prepared with

new measurement methods being developed in parallel.

References

1. C. Harrison, J.T. Cabral, C.M. Stafford, A. Karim,

and E.J. Amis, (submitted).

2. Cabral, et al., (in preparation).

3. Sehgal, et. al., (in preparation).

4. J.K. Harris, et al., Langmuir, 2002, 18, 5337–5342.

Contributors and Collaborators

J.T. Cabral, A.I. Norman, A. Karim, E.J. Amis

(Polymers Division, NIST)

An example of such a device is described in the

Nanoscale Manufacturing project in this report and

is the basis of a Focused Project established with industrial

collaborators through the NCMC to develop an HT method

to measure interfacial tension. Additional current

applications include devices for in situ polymerization,

combinatorial mixers, stamps for microcontact printing,[3]
25

Combinatorial Methods

Combinatorial Epoxy Curing Library: Correlating Network

Formation, Chemical Conversion, and Adhesion

The performance of epoxy-based advanced

composites, coatings, and structural adhesives

depends strongly on the resin curing process.

Thus, combinatorial and high-throughput methods

are ideally suited to study the curing process.

We are working to correlate epoxy film curing

properties as a function of two processing

variables using three independent techniques:

FTIR reflectance microscopy, confocal microscopy,

and axisymmetric adhesion tests.

Aaron M. Forster, Naomi Eidelman, and

Dharmaraj Raghavan

Using gradient and high-throughput techniques,

we analyzed epoxy curing as a function of both

temperature and time. Diglycidyl ether bisphenol A

epoxy resin was mixed with fluorescent dye

(4 dimethylamino-4’-nitrostilbene) and curing agent

(2,4,6-tri(dimethyl amino methyl) phenol) and deposited

via flow coating on a glass substrate. The epoxy film

sample was cured on a temperature gradient stage,

(50 to 100) oC, for (15, 30, 45, 60, and 180) min, and

39 h. The epoxy film was mapped ex-situ by Fourier

Transform Infrared (FTIR)-reflectance microscopy

and confocal microscopy, in conjunction with adhesion

tests (contact with polydimethylsiloxane (PDMS)

hemispherical lens) to provide chemical, physical,

and interfacial information on the epoxy film during

the curing process.

The chemical conversion of epoxy groups is

measured with FTIR. As shown in Figure 1, color

maps of epoxy conversion quantify chemical changes

as a function of the two variables.

Confocal microscopy measurements of fluorescence

intensity (emission maximum) characterize epoxy

network formation. The cured epoxy film network

restricts fluorophore motion, which leads to a higher

fluorescence intensity relative to the uncured epoxy

film (see Figure 2).

Figure 1: FTIR maps of an epoxy film at different curing

temperatures and times. The colors indicate percent curing.

Adhesion measurements probe the chemical

and mechanical properties near the interface. These

properties change as the epoxy film cures. The work

of adhesion to detach a PDMS lens from the epoxy

surface is shown in Figure 3.

Future work will focus on: the quantitative

comparison between these independent techniques,

the epoxy network structure at low- and high-curing

temperatures, and the epoxy-PDMS interface to better

correlate adhesion measurements to epoxy properties.

Contributors and Collaborators

A. Karim, E.J. Amis (Polymers Division, NIST);

N. Eidelman (American Dental Association Foundation,

PRC, NIST); D. Ragahavan (Howard University)

Figure 2: The epoxy resin film exhibits increases in the fluorescence

intensity at higher curing temperatures or longer curing times.

Figure 3: The epoxy resin film is tackier at low temperatures and

short curing times, which leads to a larger work of adhesion.
26

NIST Combinatorial Methods Center (NCMC)

A Partner in Accelerating Materials Research

Combinatorial and high-throughput (C&HT)

techniques hold great potential for materials

research, but significant barriers prevent the

widespread adoption of these revolutionary

methods. Through responsive outreach and

creative, cost-effective measurement solutions,

the NIST Combinatorial Methods Center strives

to ease the acquisition of C&HT techniques by

the materials research community.

Cher H. Davis and Michael J. Fasolka

In response to these needs, the NCMC is building

a model C&HT informatics system in its laboratory

facilities. Constructed with open-source code, the NCMC

system provides transparent examples of informatics

infrastructure. In addition, the NCMC endeavors to help

create data interchange format standards for the C&HT

materials research community. Both efforts were

highlighted at NCMC-3: Combinatorial informatics, held

at NIST on May 22–23, 2003. This workshop outlined

issues in C&HT informatics and several NIST XML-based

interchange formats relevant to materials research.

NCMC-3 culminated with the formation of the

Combinatorial Materials Research Data Standards

(CMRDS) Working Group — a first success toward

establishing data standards for the C&HT materials

community. Ten NCMC-3 attendees volunteered

to serve on CMRDS committees, which are aimed

at identifying opportunities (e.g., XML) and at

defining components for a data interchange

format. For details, see the CMRDS website at

http://polymers.msel.nist.gov/combi/cmrds.html.

The NIST Combinatorial Methods Center (NCMC)

— now in its second year — has attracted

16 member partners from industry and government. Since

its inception, the NCMC has tailored its research and

outreach towards current and emerging industrial needs

in C&HT methods. As part of its FY2003 outreach, the

NCMC organized three workshops. The first, NCMC-2,

was held October 7–8, 2002 at NIST. NCMC-2 related

NCMC-developed C&HT measurement methods for

mechanical properties and adhesion (including SIEBIMM,

see associated Highlight). In addition, the NCMC-2

program included a plenary symposium, facilities tours,

and a panel discussion that revealed industrial needs for a

Focused Project in HT Interfacial Tension Measurements

(now launched, see http://www.nist.gov/combi).

 Two additional workshops were aimed at initiating

NCMC actions in C&HT Informatics. Needs in the field

were gleaned at the NCMC Combinatorial Informatics

industrial symposium held in conjunction with a

Knowledge Foundation Meeting on February 19, 2003 in

San Jose, CA. Analysis of industry concerns indicated

two areas that presented a NIST role. First, industry

requires examples of how to integrate automated

fabrication instruments, characterization devices, and

analysis routines into a database-centered informatics

system suitable for C&HT research. Second,

interoperability barriers hamper informatics system

development. In particular, the lack of a common data

interchange format greatly complicates the integration

of devices from disparate vendor sources into a

coherent C&HT system.

FY2004 promises sustained effort and new

directions from the NCMC. NCMC-4: Polymer

Formulations, to be held October 6–7 2003, will feature

C&HT measurement strategies for complex fluids and

sessions dedicated to the Interfacial Tension Focused

Project and the CMRDS Working Group. Moreover,

new Focused Projects in Formulations and Adhesion

will be launched. In addition, a new NCMC effort in

nanotechnology will create reference substrates

designed to test and calibrate advanced scanning probe

microscopy measurements. For more information

on these efforts and other NCMC programs, see

http://www.nist.gov/combi.

“As Honeywell Specialty Materials initiates our combinatorial

effort, NIST offers an invaluable resource [as to] what can be

done, and how to go about it. The NCMC clearly demonstrates

that a combinatorial effort does not imply multi-million dollar

expenditures. . .”

— S. Curran, A. Signorelli, Honeywell International

“The people of the NCMC are developing elegant, innovative

screens. I think we’re getting more than our money’s worth.”

— M.S. Vratsanos, Air Products and Chemicals

“[NIST is] doing a great job! The NCMC is an opportunity for

us to benefit from the excellent work being conducted by that

group. . .. In the long term, this technology could potentially

change the way R&D is conducted across the world.”

— Y. Dar, ICI/National Starch & Chemicals

Contributors and Collaborators

A. Karim, W. Zhang, K.L. Beers, C. Stafford,

A. Forster, H.J. Walls, J.T. Cabral, A.I. Norman,

D.H.A. Chiche, E.J. Amis (Polymers Division, NIST)

Combinatorial Methods

NCMC Members (*New in FY2003):

3M ExxonMobil Research

Air Force Research Lab Honeywell International

Accelrys Inc.* ICI/National Starch & Chemicals

Air Products & Chemicals Michelin*

Akzo Nobel PPG Industries*

BASF Procter & Gamble

Bayer Polymers Rhodia

Dow Chemical Company* Symyx Technologies*
27

Program Overview

Interface of Materials with Biology

New materials and devices are radically

changing the medical treatment of injury and disease,

yet because of the rapid pace of this segment of

the materials industry, an adequate measurement

infrastructure does not yet exist. The program

on the Interface of Materials with Biology develops

measurement methods, standards, and fundamental

scientific understanding at the interface between

materials science and biological science. Within the

health care industry, we focus on dental and medical

sectors that apply synthetic materials for replacement,

restoration, and regeneration of damaged or diseased

tissue. Three primary foci exist within this program:

biocompatibility, materials properties, and materials

science techniques applied to biological systems.

Whether the medical issue involves implanting

a hip or knee joint prosthesis, a synthetic bone graft,

or a tissue engineering scaffold into the human body,

one of the primary issues is biocompatibility. By using

our expertise in materials science, we are working

to develop suitable Reference Materials (RM) for

investigating biocompatibility and implant suitability.

Research has focused on measuring the cellular

response to powders and bulk materials to identify

suitable candidates. We are collaborating with the

American Dental Association Foundation (ADAF)

to develop metrology methods to characterize the

biocompatibility of synthetic bone grafts. Quantitative

methods being developed include assays for adhesion,

viability, proliferation, and differentiation of bone cells,

as well as optical coherence tomography and confocal

microscopy for measuring tissue ingrowth. We are

developing biochemical assays to quantify inflammatory

responses to synthetic materials. Finally, current

research is working to bridge the gap between

knowledge generation by cell biologists and product

development in industry. In collaboration with the

Chemical Science and Technology Laboratory, we are

developing measurement methodologies and reference

materials to use in assessing interactions in complex

systems of living cells with synthetic materials.

The expected outcomes of this work are reference

substrates that induce specific cellular responses and

engineered DNA vectors to act as fluorescent reporters

of cellular responses.

In addition to the issue of biocompatibility, it is

critical that the materials can withstand the mechanical

and environmental stresses placed on them. For

metallic implants, one concern is the corrosion pitting

resistance of the implant materials and the associated

potential for stress corrosion cracking (SCC). To

address this issue, metal standards are being subjected

to a simulated biological environment which will then

be used to develop tests to assess the susceptibility

for SCC.

Mechanical properties issues also arise when

considering synthetic bone grafts and tissue engineering

scaffolds. In addition to traditional bulk mechanical

property measurements, combinatorial approaches

are used to identify compositions and surface features

that affect properties such as biocompatibility and

mechanical durability. Finally, because the dental

industry is primarily composed of small manufacturers

with limited R&D capability, collaborations with

the ADAF, located in MSEL, are filling the gap

by developing improved materials and techniques,

patenting and licensing these inventions, and, most

importantly, providing a technical foundation.

Research focuses on improved understanding

of the synergistic interaction of the phases of

polymer-based composites and the mechanisms of

adhesion to dentin and enamel. This approach will

ultimately lead to materials with improved durability,

toughness, and adhesion to contiguous tooth structure.

In this era of interdisciplinary approach to

research, we provide an added dimension. By taking

a physical/mechanical approach to how cells function,

respond, and remodel in interaction with synthetic

materials, we can provide skill sets typically absent

in the biomedical community. Our concentration on

mechanical property metrology extends to biological

systems, spanning a considerable size range from

individual neurons and muscle cells to complete

pulmonary arteries. This necessitates the development

of unique mechanical testing platforms and application

of a materials science approach to understanding

integrated properties.

Fundamental to much of the work in this program

is the recognition that surfaces and interfaces play a

critical role in biological systems and, in particular,

in the interactions of synthetic or designed materials

with biological systems and function. By applying

the expertise in the NIST Materials Science and

Engineering Laboratory to characterization of surfaces

and interactions at interfaces in biomaterials, we will

accelerate the introduction of improved materials and

help provide the means to assure quality control that is

critical to this industry.

Contact: Newell R. Washburn
28

Bioactive Polymeric Composites for Mineralized

Tissue Regeneration

There is a growing interest in the biomaterials

community about polymer-based bioactive

materials that can promote the preservation/

remineralization of hard dental tissues, i.e.,

enamel, dentin, and bone. As part of a joint

research effort with the American Dental

Association Foundation–Paffenbarger Research

Center (supported by the National Institute of

Dental and Craniofacial Research), NIST has

been investigating various types of polymeric

calcium phosphate composites. As a result, NIST

is providing the dental industry and profession

with a comprehensive knowledge base regarding

these potentially bioactive materials that will help

elucidate their in-vitro and in-vivo performance.

Joseph M. Antonucci

Calcium phosphates are of special interest to oral

biology, dentistry, and medicine since they occur

in normal skeletal tissues and in the pathological

calcification of nonmineralized tissues and synthetic

materials. Crystalline hydroxyapatite (HAP) is the

structural prototype of the major mineral component

of teeth and bones. Amorphous calcium phosphate

(ACP), a postulated precursor to biological HAP, shows

high solubility/degradability in aqueous media, readily

liberating calcium and phosphate ions, and transforming

to crystalline apatitic calcium phosphate. These

properties suggested its use as a bioactive filler in

polymeric dental composites.

In recent studies, we have applied solid-state 1H

NMR methods to better characterize ACP. We can

distinguish between rigid waters of hydration in the

lattice, plus both strongly and weakly bound water.

Hydroxy protons in apatitic structures can also be

identified. In ACP, about 2/3 of the protons are in rigid

waters of hydration; however, the fractions of strongly

and weakly bound water vary with pyrophosphate, an

ACP stabilizer used to slow the conversion to apatitic

structures.

In other studies, we have examined the effect of

acidic comonomers on the degree of vinyl conversion

(FTIR) and mechanical strength (biaxial flexural strength)

of ACP composites formulated with equal amounts of

2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy) phenyl]

(Bis-GMA) and triethylene glycol dimethacrylate

(TEGDMA). As expected, the conversion values

for the composites are somewhat reduced compared

to those of the unfilled copolymers. Significantly,

with these systems, the differentials between the

vinyl conversion of the unfilled copolymers and their

composites were smaller than that observed for

other types of ternary Bis-GMA/TEGDMA systems.

With one acidic termonomer system, where the acid

monomer was relatively hydrophobic, a significant

enhancement of biaxial flexure strength, even after

prolonged aqueous storage, was observed, indicating

the effect of chemical structure of the polymer matrix

on interfacial properties.

A problem with dental composites of all types is

their lack of sufficient toughness to resist cracking

under masticatory stress. This can be especially critical

in the case of ACP composites that are significantly

mechanically weaker than glass-filled composites.

In a preliminary study, we found that a urethane

dimethacrylate commonly used in formulating dental

composites can be blended (3/1 ratio by mass) with

a more flexible PEG400 diol urethane dimethacrylate

to yield tough ACP composites (as measured by

stress–strain curves). In addition, it was found that

the addition of small amounts (0.1 % mass fraction) of

chopped polyethylene fibers resulted in composites that

did not fail catastrophically under biaxial stress while

maintaining their biaxial flexure strength (see Figure 1).

It is expected that this developing knowledge base will

aid future research and prove of value to manufacturers

in their design of more efficacious therapeutic dental

and biomaterials.

Contributors and Collaborators

W.G. McDonough, D. Vanderhart, D. Liu (Polymers

Division, NIST); D. Skrtic, J.B. Quinn, G.E. Schumacher

(American Dental Association Foundation–Paffenbarger

Research Center); W.F. Regnault (FDA, CDRH)

Figure 1: ACP composite disk (16 mm D x 1 mm H) after biaxial

flexure loading. Note the polyethylene fibers bridging the crack

near the center of the fractured disk.

Interface of Materials with Biology
29

High-Throughput Biocompatibility Screening of Polymer Blends

The Polymers Division is developing

high-throughput methods for the rapid screening

of biomaterials. We have prepared single samples

with gradients of polymer composition in the

form of a film onto which cells can be cultured.

Measurement of cellular response on these

gradients allows rapid characterization of cellular

response as a function of material properties.

Carl G. Simon, Jr. and Newell R. Washburn

Polymers are frequently blended to optimize material

properties such as strength, flexibility, morphology

and crystallinity. This includes polymers used for

biomedical applications. For instance, there are

commercially available degradable sutures made of

Polyglactin 910, which is a blend of poly(L-lactide)

(PLLA) and poly(lactide-co-glycolide). In order to

speed the development of new biomaterials, we are

developing high-throughput methods for characterizing

the biocompatibility of polymer blends.

Preparation of individual polymer specimens of

discreet compositions that systematically span a

significant range of properties can be tedious and

time-consuming. To address this, we have used a

high-throughput technique that involves the creation of

a gradient of polymer composition in the form of a film

to examine cell response to blends of two polymers.

Cell responses such as adhesion, morphology,

proliferation, and differentiation can be evaluated after

culturing cells on the polymer composition gradients.

Compositions that support cell function can be rapidly

identified to provide an optimal blend composition for

use in tissue engineered medical products.

mixture changes over time. There, we use a syringe to

sample the solution during mixing, which results in a

composition gradient along the barrel of the syringe.

The gradient solution is then quickly deposited in a line

on a flat substrate and spread into a film using a knife.

The gradients are characterized with

microspectroscopic fourier transform infrared

(FTIR) spectroscopy to map composition of the

entire gradient library (Figure 1) and atomic force

microscopy (AFM) to map surface topology.

FTIR reveals that the technique is feasible and makes

consistent gradients. AFM shows that the surface

roughness varies with composition. The PLLA-rich

end of the gradient (RMS ≈ 10 nm ) is about 10 times

rougher than the PDLLA-rich end (RMS ≈ 1 nm ).

We have made composition gradients of two

biodegradable polymers, PLLA and poly(D,L-lactide)

(PDLLA). The pure polymer solutions are separately

and simultaneously infused into, and withdrawn from,

a mixing vial such that the composition of the resulting

Figure 1: FTIR map of a PLLA–PDLLA composition gradient.

Figure 2: Osteoblasts growing on a PLLA spherulite.

Cellular response is characterized on the library

as a function of local material parameters. We are

using automated fluorescence microscopy to correlate

changes in cell shape, cytoskeleton development, focal

adhesions, and proliferation, and correlating these

with substrate topography. Preliminary studies with

osteoblast-like cells (MC3T3-E1) suggest that they

proliferate faster on PDLLA. This technique should

accelerate materials research for tissue engineering by

providing a rapid technique for investigators to screen

polymer blends for their ability to support cell function.

Contributors and Collaborators

A. Karim, S. Kennedy, A. Sehgal, C. Khatri,

F. Wang, C. Stafford and M. Weir (Polymers Division,

NIST); N. Eidelman (American Dental Association)

Interface of Materials with Biology
30

Measurement of Cellular Response to Three-Dimensional

Scaffolds for Tissue Engineering

In the Polymers Division, we are developing

measurement methods for determining

structure–property relationships for tissue

engineering scaffolds. The performance of this

new class of medical devices is a complex function

of scaffold composition, geometry, and embedded

growth factors. We have established bioreactor

culturing methods capable of promoting tissue

development in these three-dimensional scaffolds

and are characterizing the influence of systematic

variations in scaffold geometry on bone

development.

Newell Washburn and James Cooper

The tissue engineering industry is faced with many

measurement issues when trying to characterize

porous, three-dimensional (3-D) scaffolds. Porous,

3-D scaffolds are needed to regenerate tissue growth

within the implant for stronger fixation. Unlike flat

surfaces used to grow cells in culture, normal cells

and tissue in the body are in a three-dimensional

environment that determines cellular response.

Placing the cells in a 3-D environment sends signals

to the cells that allow the cells to differentiate to the

correct phenotype. We are developing measurement

methods and protocols to monitor cell migration and

matrix formation within scaffolds as a function of

scaffold geometry.

The ability to change the porosity and poreinterconnectivity of the 3-D scaffold will give more

insight into the environment needed for proper cellular

response and varies the measurement environments for

identification of cells and its components. In Figure 1,

representative images of 3-D polymeric scaffolds

prepared by co-extrusion show changing pore

interconnectivity with pore diameters > 100 μm.

The rate at which the cells migrate into a 3-D

scaffold and initiate matrix formation is crucial to the

development of tissue engineered scaffolds. Once

implanted, the cells within the 3-D scaffolds must send

signals to outer migrating cells to reduce the inflammatory

response and start the remodeling phase of healing.

In order to measure cellular response to dynamic

environments, we use a perfusion bioreactor (Figure 2).

The perfusion bioreactor allows simultaneous nutrient

supply and removal of cellular waste. The bioreactors

also stimulate the cells with shear forces due to the

flow of media. In addition, other studies have shown

an increase in cell proliferation and matrix production

by using bioreactor systems.

Figure 1: Cross-sections of 3-D polymer scaffolds showing the

capability to control pore-interconnectivity in order to measure

cellular response to changing porosity and pore diameters

(small to large).

Figure 2: Perfusion bioreactor used to expose cells to dynamic

flow conditions.

Once seeded on the structure, cell viability,

proliferation, and infiltration into the porous scaffold

network is important to the development of new tissue.

Quantitative 3-D imaging techniques are being developed

to measure organization of cells and extra-cellular

matrix components to determine migration and

differentiation. The fluorescence image in Figure 3

shows MC3T3–E1 cells (osteoblastic cell line) on the

surface of a 3-D polymeric scaffold.

Contributors and Collaborators

J. Dunkers, M. Cicerone, C. Simon (Polymers

Division, NIST)

Figure 3: Fluorescent image of cell migration (cell nuclei –

orange) on the surface of 3-D PCL scaffolds (green).

Interface of Materials with Biology
31

Program Overview

Materials for Micro- and Opto-Electronics

U.S. microelectronics and related industries

are in fierce international competition to design and

produce smaller, lighter, faster, more functional,

and more reliable electronics products more quickly and

economically than ever before. At the same time, there

has been a revolution in recent years in new materials

used in all aspects of microelectronics fabrication.

Since 1994, the NIST Materials Science and

Engineering Laboratory (MSEL) has worked closely

with the U.S. semiconductor, component, packaging,

and assembly industries. These 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. 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 models of small, complex structures to

substitute for or provide guidance for experimental

measurement techniques; and

■ Develop fundamental understanding of materials

needed in future micro- and opto-electronics.

With these objectives in mind, the program

presently consists of projects led by the Metallurgy,

Polymers, Materials Reliability, and Ceramics

Divisions that examine and inform industry on key

materials-related issues. 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) at NIST. Materials

metrology needs are also identified through industry

groups and roadmaps, including the International

Technology Roadmap for Semiconductors (ITRS),

the IPC Lead-free Solder Roadmap, the National

Electronics Manufacturing Initiative (NEMI)

Roadmap, the Optoelectronics Industry Development

Association (OIDA) roadmaps, and the National

[Magnetic Data] Storage Industry Consortium (NSIC).

Although there is increasing integration

within various branches of microelectronics and

optoelectronics, the field can be considered in three

main areas. The first, microelectronics, includes

needs ranging from integrated circuit fabrication to

component packaging to final assembly. MSEL

programs address materials metrology needs in

each of these areas, including lithographic polymers

and electrodeposition of interconnects, electrical,

mechanical, and physical property measurement

of dielectrics (interlevel, packaging, and wireless

applications), and packaging and assembly processes

(lead-free solders, solder interconnect design, thermal

stress analysis, and co-fired ceramics).

The second major area is optoelectronics, which

includes work which often crosses over into electronic

and wireless applications. Projects currently address

residual stress measurement in optoelectronic films,

optical and structural characterization of wide bandgap

semiconductors, and standards development for

III–V compound semiconductors. Cross-laboratory

collaborations with EEEL figure prominently in

this work.

The third area is magnetic data storage, where

the market potential is vast and growing and the

technical challenges extreme. NSIC plans to

demonstrate a recording density of 1 terabit per

square inch — 40 times today’s level — by 2006.

To reach these goals, new materials are needed that

have smaller grain structures, can be produced as thin

films, and can be deposited uniformly and economically.

New lubricants are needed to prevent wear as spacing

between the disk and head becomes smaller than the

mean free path of air molecules. Some measurements

require calibration of magnetometers using certified

magnetic standards in several different shapes and

magnetic strengths, and with a wide range in magnetic

character. MSEL is working with the magnetic

recording industry to develop measurement tools,

modeling software, and standards to help achieve

these goals, with MSEL, the Electronics and Electrical

Engineering Laboratory, the Physics Laboratory,

the Information Technology Laboratory, and the

Manufacturing Engineering Laboratory working as

partners in this effort.

Contact: Frank W. Gayle
32

Characterization of Porous Low-k Dielectric Constant Thin Films

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. The methodology utilizes several

complementary experimental techniques to

measure the average pore and matrix morphology.

Pore size distributions are calculated by x-ray

reflectivity and neutron scattering porosimetry.

Methods have been developed to measure closed

pore content and matrix morphology in films having

complex structures with any morphological type.

Barry J. Bauer

The next generation of integrated circuits will require

feature sizes that demand new low-k interlayer

dielectric materials. To address problems with power

consumption, signal propagation delays, and crosstalk

between interconnects, dielectric constants need to

significantly decrease. The primary approach to low-k

dielectric materials is the introduction of nanometer

scale pores into a solid film to lower its effective

dielectric constant. While these modifications change

the dielectric constant favorably, other important

parameters such as physical strength and barrier

properties will also change, often in an unfavorable

way. Characterization of the pore structure is crucial

to the development of new dielectric materials, and

new measurement methods are necessary.

NIST provides low-k characterization using a

combination of small angle neutron scattering (SANS),

high-resolution x-ray reflectivity (HRXR), and ion

scattering techniques. These measurements are performed

directly on films supported on silicon substrates so that

processing effects can be investigated. New methods

are required, however, to provide more detailed information

necessary to complete the product development.

This year, we have continued our efforts on

characterization of current industrially relevant

materials primarily through International SEMATECH,

a consortium of microelectronics companies, but also

through other industrial partners. The technological

roadmap has progressed to a decision point at

which materials will be chosen for the next step:

the integration of low-k materials into complex

circuits. NIST has provided a considerable body of

data to make this choice possible.

To advance the measurement capabilities, we

have perfected new techniques for more thorough

and accurate film characterization. Work has been

completed on a small angle neutron scattering (SANS)

technique and instrumentation for measurement of films

that have been infused by mixtures of normal solvent

and the same solvent in which the hydrogens have

been replaced by deuterium (see Figure 1). The match

point measures where the neutron contrast matches

that of the wall material. By filling the open pores with

contrast match fluids, SANS reveals the closed pore

content and size. The relative open and closed pore

content is becoming increasingly important to low-k

applications. The same instrumentation has been used

to determine the uniformity of the wall material with

respect to remnants of porogen that remain after

incomplete thermal treatment.

This year, several projects have been completed in

response to industry needs. SANS has been used to

measure the size and volume fraction limits of damaging

“killer” pores in collaboration with Dow Chemical.

X-ray reflectivity has been used to measure the

effects of plasma treatment on film density profiles in

collaboration with Axcelis. The pore formation process

was quantified to connect pore size distributions of

the formed pores with pore size distributions of the

porogen used to generate the pores in collaboration with

Dow Chemical. A new method of calculating pore size

distributions from SANS data has been demonstrated.

Contributors and Collaborators

H. Lee, R. Hedden, C. Soles, M. Silverstein, D. Liu,

W. Wu (Polymers Division, NIST); C. Glinka (Center

for Neutron Research, NIST); J. Iacoponi, Y. Liu

(International SEMATECH); B. Landes (Dow Chemical);

C. Waldfried, O. Escorcia (Axcelis); B. Hwang, W. Gray

(Dow Corning)

Figure 1: Schematic illustrating different sample characteristics

that can be distinguished using SANS contrast match techniques.

Materials for Micro- and Opto-Electronics
33

Polymer Photoresists for Next-Generation Nanolithography

Photolithography, the process used to fabricate

integrated circuits, is the key enabler and driver

for the microelectronics industry. As lithographic

feature sizes decrease to the sub 100 nm length

scale, significant challenges arise because both

the image resolution and the thickness of the

imaging layer approach the macromolecular

dimensions characteristic of the polymers used in

the photoresist film. Unique high-spatial resolution

measurements are developed to reveal limits on

materials and processes that challenge the

development of photoresists for next generation

sub-100 nm lithography.

Eric K. Lin

Photolithography is the driving technology used by

the microelectronics industry to fabricate integrated

circuits with ever decreasing sizes. In addition, this

fabrication technology is rapidly being adopted in

emerging areas in optoelectronics and biotechnology

requiring the rapid creation of nanoscale structures.

In this process, a designed pattern is transferred to

the silicon substrate by altering the solubility of areas

of a polymeric photoresist thin film through an acid

catalyzed deprotection reaction after exposure to

radiation through a mask. To fabricate smaller features,

next generation photolithography will be processed

with wavelengths of light requiring photoresist films

less than 100 nm thick and dimensional control to

within 2 nm. Material, interface, and transport issues

arise when fabricating structures over these length

scales. To date, the materials and processes needed to

fabricate sub-100 nm features have not been selected

because of increasingly challenging technical issues.

To advance this key fabrication technology, we

work closely with industrial collaborators to develop

and apply high-spatial resolution and chemically specific

measurements to understand changes in material

properties, interfacial behavior, and process kinetics

at nanometer scales that can significantly affect the

patterning process.

This year, we have applied and enhanced unique

measurement methods to provide structural measurement

of fabricated nanoscale structures and new insight and

detail into the complex physico–chemical processes used

in advanced chemically amplified photoresists. These

methods include x-ray and neutron reflectivity (XR, NR),

small angle neutron and x-ray scattering (SANS, SAXS),

incoherent neutron scattering (INS), near-edge x-ray

absorption fine structure spectroscopy (NEXAFS),

combinatorial methods, nuclear magnetic resonance

(NMR), quartz crystal microbalance (QCM), Brillouin light

scattering (BLS), fluorescence correlation spectroscopy

(FCS), and atomic force microscopy (AFM).

Figure 1: SANS data from a model photoresist polymer in

organic solvent (green) and aqueous base developer (blue).

The peak in the blue curve shows electrostatic effects on the

chain conformation not present in the organic solvent.

Accomplishments for this past year include:

advancements in critical dimension measurement with

SAXS (see highlight); identification of polyelectrolyte

effects in photoresist dissolution (see Figure 1) and

their impact on the resolution of the structure; direct

measurement of surface segregation of a fluoropolymer

blend component to the surface of the resist film

impacting its dissolution behavior; identification of key

anti-reflection coating (ARC) components responsible

for profile control problems at the ARC-resist interface;

correlation of polymer local dynamics with transport

of water and photoacid diffusion showing the effect

of confinement on resist processing parameters; and

the first measurement of the shape and form of the

3-D deprotection volume from the reaction-diffusion

of dispersed photoacids, a key variable in model

predictions of the roughness or resolution of photoresists.

Contributors and Collaborators

C. Soles, W. Wu, R. Jones, V. Prabhu, C. Wang,

E. Jablonski, B. Vogt, M. Wang, N. Noda, F. Starr,

P. McGuiggan, D. VanderHart, C. Chiang (Polymers

Division, NIST); D. Fischer, S. Sambasivan, (Ceramics

Division, NIST); S. Satija, C. Glinka (NCNR, NIST);

D. Goldfarb, K. Temple, A. Mahorowala, M. Angelopoulos

(IBM T.J. Watson Research Center); B. Trinque, S. Burns,

C. Willson (University of Texas at Austin); R. Puligadda,

Y. Wang, C. Devadoss (Brewer Science)

Materials for Micro- and Opto-Electronics
34

Dielectric Measurements of Polymer Composite Films

in the Microwave Range

corresponding time resolved voltage waves. The new

testing procedure represents a compatible extension of

the existing standard test method but is better suited for

capacitive and/or resistive thin-film materials. It was

found that embedded passive materials do not exhibit a

constant impedance characteristic, as in conventional

dielectrics, but, rather, their impedance sharply decreases

with increasing voltage. This change in impedance

could not be detected by the conventional test methods.

Polymer composite materials with enhanced

electromagnetic properties have been identified

by the industry as essential for advancing

miniaturization and functional performance of

high-speed electronics. This project develops

dielectric metrology specific to the needs of

the electronics industry for embedded passive

materials and devices. The current focus is on the

measurement of permittivity at microwave frequencies

and impedance at high AC voltages. These unique

measurements enable the identification of the key

structural attributes that control the properties of

organic resins filled with electronic modifiers.

Jan Obrzut

I

n recent years, a broadband technique has been

 developed successfully as a standard test method

that enables dielectric measurements at microwave

frequencies. The technique is based on the observation

and theoretical analysis of the fundamental mode

propagating at high frequencies in thin-film dielectrics that

terminate a coaxial air-filled transmission line. This year,

we applied 3D numerical simulations of the electromagnetic

field to improve understanding of the measurement

and enabled an extension to frequencies up to 12 GHz.

The numerical simulations were used to identify and

quantitatively analyze the residual inductance of the film

specimens. For high-k materials with a high capacitance

density, even small residual inductance can cause resonant

oscillations, which leads to systematic uncertainties in

the measured permittivity. Results from the numerical

simulations helped formulate a closed-form expression

for the input impedance of complex thin-film materials

that is accurate up to 12 GHz. Broadband dielectric

measurements of high-k composite materials that are of

interest to bio- and nanotechnology and microelectronics

are now possible and at previously inaccessible frequencies.

In partnership with IPC, we initiated a standard test

method development and chaired the IPC-D-37d test

method subcommittee for Embedded Passive Devices.

We guided the design of the test protocol and made

arrangements with co-sponsoring member companies

for round robin evaluation. The committee forum has

recognized NIST for being the leading laboratory in the

characterization of high-k materials and for effectively

addressing the standardization needs of the emerging

electronic packaging technologies.

A suitable testing procedure has been demonstrated

for unambiguous determination of dielectric properties

at high AC voltages. The specimen voltage and

current are determined as complex quantities from the

Figure 1: Dielectric properties as a function of frequency for

normal and functionalized nanotubes in PMMA.

Our unique capability to measure the dielectric

relaxation time in the sub-nanosecond regime and

the relaxation strength for a wide range of dielectric

permittivity values is used to quantify dispersion,

alignment, and structure in nanostructured composite

materials. Figure 1 shows the dielectric properties of

two composites containing a 2 % mass fraction of

single wall carbon nanotubes (SWCT) dispersed in

poly(methyl methacrylate) (PMMA). The SWNTs were

surface-modified to affect dispersion and coupling.

Functionalized nanotubes, SWCT-f, showed an increase

in the dielectric constant and can be rationalized based on

the log mixing-rule law. In contrast, adding purified SWCT

(SWCT-p) to PMMA increases the dielectric constant by

3 orders of magnitude. Small angle neutron scattering

data indicate that this formulation exhibits a preferential

coupling within the dispersed phase where a small amount

of modifier causes a large enhancement in the properties

of the mix. These results can be utilized in advanced

engineering of plastic composites to obtain enhanced

structural, optical, thermal, and electronic properties.

Contributors and Collaborators

A. Anopchenko, K. Kano, (Polymers Division, NIST);

B. Rust (Mathematical and Computational Sciences,

NIST); R. Croswell (Motorola); D. McGregor (DuPont);

H. Wang (Michigan Technical University); K. Winey,

J. Fischer (University of Pennsylvania)

Materials for Micro- and Opto-Electronics
35

Materials Structure Characterization

Fundamental to the field of materials science and

engineering is the study of the relationships between

processing, structure, properties, and performance

of materials. Therefore, tools and techniques for

the characterization of materials structure is a

cornerstone of the field. The NIST Materials Science

and Engineering Laboratory (MSEL) has a long tradition

of supporting and developing measurement methods

and facilities for materials structure characterization.

Facilities within MSEL include optical and electron

microscopy, optical and electron scattering and

diffraction, a state-of-the-art x-ray diffractometer, the

NIST Center for Neutron Research, and experimental

stations at the National Synchrotron Light Source

(NSLS) at Brookhaven Laboratory and at the Advanced

Photon Source (APS) at Argonne National Laboratory.

At the NSLS, NIST operates a soft x-ray station in

partnership with Dow and Brookhaven National

Laboratory. At the APS, NIST is a partner with the

University of Illinois at Urbana/Champaign, Oak Ridge

National Laboratory, and UOP in a collaboration called

UNICAT. At both facilities, NIST scientists and

researchers from industry, universities, and government

laboratories perform state-of-the-art measurements on

a wide range of advanced materials. NIST scientists

have consistently advanced the limits of these facilities

in order to improve spatial resolution and sensitivity

needed, for example, to interrogate the microstructure

of both highly anisotropic and/or gradient materials

such as advanced thermal coatings and fuel cell

systems. Studies currently underway at these facilities

include: in-situ measurements of nanoparticle

production; structure and dispersion of carbon

nanotubes; three-dimensional imaging of natural and

artificial tissues; surface and subsurface damage in

UV lithography optics; strain-induced ferroelectric

transitions in thin films; and determination of molecular

orientation and bond concentration on chemically

heterogeneous surfaces.

The materials characterization program has

a strong emphasis on electron microscopy. The MSEL

Electron Microscopy Facility provides structure and

compositional characterization of a wide range of

materials. The facility consists of two transmission

electron microscopes (TEMs), three scanning electron

microscopes (SEMs), a specimen preparation laboratory,

and an image analysis/computational laboratory.

The JEM3010 TEM resolves the atomic structure and

employs an energy selecting imaging filter and x-ray

detector (EDS) for analytical characterization of thin

foil specimens. The JSM6400 SEM employs electron

backscattered diffraction /phase identification and EDS

systems to characterize the texture and composition

of materials. Highlights from the facility for FY2003

include: the computer domain is now active, providing

streamlined user access and network file storage;

a research collaboration with the NIST Semiconductor

Electronics Division is underway to characterize

quantum effects in confined Si devices; the size and

shape of III–V quantum dots are characterized with

the NIST Optoelectronics Division; and composition

maps of electrodeposited nanowires with tunable

magnetic properties are generated in collaboration

with Johns Hopkins University.

This MSEL program also incorporates standards

activities. A state-of-the-art x-ray diffractometer has

been developed to study the metrology of powder

diffraction in order to develop the next generation of

diffraction standard reference materials. A variety of

standard reference materials (SRMs) needed by the

U.S. polymers industry, research laboratories, and

other federal agencies have recently been developed:

polyethylene of narrow mass distribution; nonlinear

fluids for rheological measurements; melt flow

standards; and the first reference biomaterial, an

orthopedic grade ultra-high molecular weight

polyethylene.

Recent program activities utilize matrix-assisted laser

desorption/ionization time-of-flight mass spectrometry

(MS) to address the need for improved characterization

of the molecular structure of polyolefins, a dominant

commercial polymer. This work has extended the

upper mass limit detectable by MS to 15,000 g/mol

and, by observing individual oligomeric species by

mass, has revealed details of the molecular structure.

A major cross-cutting activity within this program

is the multi-scale, multi-modal imaging and visualization

project. The goal of this project is to combine disparate

sets of 3-D imaging data that contain complementary

information on overlapping length scales to produce

an interactive visualization scheme for multivariate

data sets. This year focused on further improvements

and additions to the suite of imaging tools for tissue

engineering metrology. Osteoblasts cultured in a

poly (ε-caprolactone) scaffold have been imaged,

demonstrating the advantages of optical coherence

and confocal fluorescence microscopies over

conventional laser scanning confocal microscopy.

This instrument was upgraded by completely rebuilding

the image acquisition software, hardware, and optical

train. These improvements enabled an increase in

image acquisition speed (2X) and accuracy

(from 5 μm to 360 nm).

Contact: David R. Black

Program Overview
36

Coherent Anti-Stokes Raman Micro-spectroscopy (μ-CARS)

for Understanding Tissue Growth in Scaffold Constructs

Effective and efficient regenerative medicine efforts

require a thorough understanding of cell response

to scaffold morphology, surface characteristics, and

local biochemical conditions. We are developing a

fast, high-resolution chemical microscopy technique

that allows us to monitor in situ cell activity and

growth along with local scaffold morphology, and

relevant surface and solution chemical components

in a manner that is non-invasive to delicate, rapidly

dividing cells such as found in tissue scaffold

constructs. This technique will allow correlations

to be made between cells and environmental factors

at the cellular level.

Marcus T. Cicerone and Tak W. Kee

An important approach to regenerative medicine

 involves the use of tissue scaffolds as platforms

for cell growth. These scaffolds serve to guide the

shape and structure of the final regenerated tissue

structure and often serve to provide structural support

to surrounding tissues while the target tissue regenerates.

These scaffolds may take the form of extruded

polymer blends, microprinted or electrospun

structures, or hydrogels.

A nominal aim in design of tissue scaffolds is to make

the local environment of the cells conducive to their normal

growth and development. Presently, the parameters for

the physical and chemical design of these constructs are

not well understood. Furthermore, existing volumetric

imaging systems that have chemical sensitivity sufficient

for tracking cell behavior, such as Magnetic Resonance

Imaging (MRI) and Computed Axial Tomography (CAT),

do not have the spatial resolution to track individual cells

or detect local scaffold structure. A non-invasive imaging

methodology that provided sub-micrometer spatial

resolution, volumetric imaging, and chemical sensitivity

would greatly facilitate progress in understanding cell

response to tissue scaffold environment.

Coherent anti-Stokes Raman spectroscopy (CARS)

is a vibrational spectroscopy, similar to infra-red (IR)

or spontaneous Raman spectroscopy, and thus has

potential for excellent chemical specificity. Infrared

microscopy cannot be used to track single cells due to

its poor spatial resolution. Raman microscopy is too

inefficient, and its use leads to cell damage. CARS, on

the other hand, can be used to chemically interrogate

single-cells in a repetitive manner without adverse

effects. Unlike IR and Raman, CARS is a multi-photon

spectroscopy, requiring a pump pulse to excite

molecules into a virtual electronic state and a second

(Stokes) pulse to induce relaxation into vibrationally

excited states. The identity of those states is then

reported by the system’s response to a third pulse

(pump). A schematic diagram of the CARS process

is given in Figure 1.

Figure 1: Schematic of CARS process. Upward arrows:

absorption. Downward arrows: emission. ωp : pump light.

ωS : Stokes light. ωaS : emitted anti-Stokes light.

In order to realize the potential for chemical specificity

with CARS, a full vibrational spectrum needs to be

generated, requiring a broadband Stokes pulse. This

has not been done before with a CARS microscope.

This year, we solved several technical problems

associated with the broadband Stokes light and started

building the CARS microscope. The technical problems

resolved are: generation of broadband light via photonic

crystal fiber, compensation for chromatic aberration so

that the entire 200 nm band of Stokes and pulse light

can be focused at the same spot to within 300 nm, and

the rapid acquisition of spectral data, which will require

modification of a commercial CCD camera.

Our long-term goal for this instrument is to use it for

in situ monitoring of cell growth in tissue scaffolds. This

will include acquisition of broadband Raman spectra from

cells, medium, and scaffold, and application of multivariate

analysis (MVA) techniques for the rapid “decoding” of

the spectra to obtain high-resolution chemical information.

Our short-term goals include developing the MVA model

for sorting out the spectra and obtaining vibrational spectra

that are characteristic of known cell response to

well-controlled stimuli.

Contributors and Collaborators

A. Sehgal (Polymers Division, MSEL); L. Richter

(Surface and Microanalysis Science Division, CSTL);

R. Tuan, W.-J. Li (NIH/NIAMS); D.M. Zhang (Purdue

University); W. Wadsworth (University of Bath)

Materials Structure Characterization
37

Polymer Standards

Producers, processors and users of synthetic

polymers use polymer standards for calibration of

instruments, assessment of laboratory proficiency,

test method development, and materials improvement.

The objectives of this project are to: assure

continuity of NIST Standard reference materials

by recertifying standards as stock is depleted;

develop a database system on the properties

of biomaterials; measure material properties of

polymers used in intraocular lenses for inclusion

in a reference database and for producing

reference biomaterials; and prepare a method

for analysis of polystyrene by mass spectrometry

and submit to various Standards Developing

Organizations (SDO) (ASTM, DIN, ISO and JIST)

for introduction into the standard test method

literature.

Bruno Fanconi and Charles Guttman

Reference Materials, RM, and Standard Reference

 Materials, SRM, are produced to address needs

of the producers, processors, and users of synthetic

polymers for calibration of instruments, assessment

of laboratory proficiency, test method development,

and materials development. Two melt flow rate

standards have been recertified for use by producers

and processors to calibrate instruments used to assess

the processibility of polymer resins. A second standard

polymer fluid, SRM 2491, was issued by NIST.

The standard, certified for rheological properties,

serves the needs of instrument manufacturers and

testing laboratories as secondary standards for

calibrating viscometers. Also issued in FY 2003 is

SRM 2888, the first polymer molecular mass standard

produced with the complete mass spectrum as ancillary

data. This standard resulted from a collaborative effort

among standards laboratories in Europe, the U.S., and

Japan to establish a standard protocol for measurement

of the mass distribution of synthetic polymers by mass

spectrometry.

Producers of polyolefins are achieving property

enhancements through control of branch architecture.

This development has intensified the need for polymer

standards certified for branch content. The ultimate

solution to this need may come from development of

new methods for characterizing branching, such as

polymer mass spectrometry. In the near term, we

exploited the wealth of characterization data in the

literature of SRM 1476, a branched polyethylene

that was formerly issued by NIST as a melt flow rate

standard. Although the remaining supply of resin from

which SRM 1476 was produced is insufficient for

a melt flow standard, it is adequate for molecular

standards. Among the characterization data published

on SRM 1476 are results of round-robin investigations

of branching characterization by chromatographic

methods. This polymer, SRM 1476, has become

a de facto branch standard and is referred to in the

scientific literature as such. The plan is to certify the

intrinsic viscosity and size by light scattering in addition

to providing ancillary information on the branch content

by high-resolution solution state Nuclear Magnetic

Resonance (NMR).

To support the growing need for reference

biomaterials, NIST released RM 8457, a medical grade

ultra-high molecular weight polyethylene, UHMWPE,

in the form of 0.5 cm cubes. The reference material

supports efforts in ASTM to develop an improved test

method for determination of degree of crosslinking

induced by irradiation of UHMWPE. Manufacturers of

medical products made of UHMWPE are researching

the use of ionizing radiation to improve wear resistance.

In collaboration with vendors of intraocular lens (IOL)

materials, testing laboratories, the National Institutes of

Health, and the LSU Medical School, data acquisition

has commenced on a series of IOL polymers for the

purpose of adding these to a reference material

database, which is under development. The intent is

to certify these IOL biomaterials as NIST reference

materials to aid research and development of improved

materials and for use in standards development. Active

participation in ASTM committee F4 seeks to expedite

introduction of reference tissue scaffolds to aid in the

development of characterization methods for their

structure and properties. Several NIST workshops

dealing with biomaterials identified this pursuit to be

of high priority.

In addition to the reference biomaterials/data

activities, the group has been active in planning for

polymers-related standards conferences and workshops.

These have been primarily with the ASTM and include

a workshop on cleanliness of medical implants (2003),

planning for a symposium on cleanliness of medical

implants (2005), a symposium on cell-materials

signaling (2003), and a workshop on Uncertainty,

Precision and Bias (2006).

Contributors and Collaborators

W. Blair, K. Flynn, J. Maurey, J. Tesk (Polymers

Division, NIST); W. Guthrie, S. Leigh (Statistical

Engineering Division, NIST)

Materials Structure Characterization
38

Saturated hydrocarbon polymers dominate

the commercial marketplace. A polymer’s

molecular-mass distribution is critical in

determining its performance properties. Mass

spectrometry is currently the most promising

method for obtaining accurate absolute molecular

mass distributions. Here we address the difficulties

in forming intact, gas-phase macromolecular

ions of these critical materials.

William E. Wallace

Molecular mass distribution measurement by mass

 spectrometry (MS) requires the formation of

intact macromolecular ions in the gas phase. This is

typically accomplished by the gas-phase association

of metal cations (Na+, K+, Cu+, Ag+, etc.) with polar

or polarizable functional groups on the polymer.

Before we began this project, polymers that lack such

functionality (like polyethylene and polypropylene) were

not amenable to mass spectrometric characterization.

In the past year, we have advanced two novel methods

of polyolefin macromolecular ion formation: covalent

cationization and organometallic cationization.

Covalent cationization works on the principle that

saturated polyolefins, regardless of the synthetic route,

typically contain some fraction of unsaturated vinyl

end-groups. Through ex situ preparative means, an

organic cation is covalently bonded to this end-group

to produce the necessary ionization for the creation of

intact gas-phase macromolecules by matrix-assisted

laser desorption/ionization (MALDI). After optimizing

the covalent cationization chemistry, ions as high as

15,000 u were placed in the gas phase; however, this

mass limit could not be exceeded even with polyolefin

materials whose extent of chemical modification had

been positively verified by Nuclear Magnetic Resonance

(NMR) and Fourier Transform Infrared (FTIR)

spectroscopies. Furthermore, an analogous study

demonstrated successful MS analysis of high-mass

polystyrene (Mn ≈ 40 ku) confirming the general

validity of the ionization method. Confident in the

utility of covalent cationization for macromolecular ion

generation, our focus turned toward physical aspects

of polyolefins.

The high crystallinity of linear polyethylenes may be

a significant barrier to the formation of single-oligomer

gas-phase ions. To overcome this barrier, a new mass

spectrometer with a heated sample stage was acquired,

Polyolefin Mass Spectrometry

installed, and tested. This will allow in situ heating of

the polyethylene to above its melting temperature, thus

eliminating crystallinity as a barrier to macromolecular

ion generation.

In the area of organometallic cationization the

charging agent of choice, the η5-cyclopentadienyl

cobalt cation (CpCo•+), was shown by Fourier

Transform Mass Spectrometry (FTMS), to

successfully charge alkanes up to C60H122 (mass

843 u) by double-dehydrogenation with no evidence of

carbon–carbon bond cleavage. Recently, the method

was extended to waxes confirming the use of this

ionization technique on polydisperse alkane mixtures.

Figure 1: The FTMS spectrum above shows the gas-phase

reaction of pristane with the CpCo•+ ion. (AU represents

arbitrary units of intensity.)

In an exciting new development, organometallic

cationization was found to be branch-point sensitive.

In studies of pristane (see Figure 1), both doubleand single-dehydrogenation were observed in strong

contrast to linear alkanes where only the doubledehydrogenation reaction is observed. This opens

the possibility for mass spectrometric studies where

the number of branch points in a polyolefin may be

counted on an oligomer-by-oligomer basis.

Contributors and Collaborators

B.J. Bauer, W.R. Blair, H.C.M. Byrd, B.M. Fanconi,

K.M. Flynn, C.M. Guttman, S. Lin-Gibson,

D.L. Vanderhart, S.J. Wetzel (Polymers Division,

NIST); J.E. Girard (American University); D.R. Ridge

(University of Delaware)

Materials Structure Characterization
39

Program Overview

Nanocharacterization

The emphasis on nanotechnology around the world

and the successful implementation of the National

Nanotechnology Initiative in the U.S. are accelerating

the development of science and technology at the

nanoscale. Nanotechnology is expected to play a key

role within the next 10 years in a wide spectrum of

industry sectors including manufacturing, information

technology, electronics, and healthcare. Novel devices

at the micro- and nanoscale will become increasingly

important in all of these industries. The ability to

measure dimensions, characterize materials, and

elucidate structures of new and novel materials at

the nanoscale will be critical to the advancement of

nanotechnology. In addition, one of the exciting

prospects of nanotechnology lies in the ability of

molecules or particles, under specific conditions, to

self-assemble to form new materials with unusual

properties. Successful development of these new

materials will require the ability to monitor such

processes at the nanoscale in real time. Metrology,

the science of measurement, is therefore the foundation

of nanotechnology. Standards and reference materials

will also provide essential infrastructural support to

this emerging technology.

The objective of the program in the NIST Materials

Science and Engineering Laboratory (MSEL) is to

develop basic measurement metrology at the nanoscale

for the determination of bulk and surface material

properties and for process monitoring. Measurement

methods are being developed for use in conjunction

with new instrumentation and calibration artifacts.

The scope of the program encompasses metals,

ceramics, and polymers in various forms — particles,

thin films, nanotubes, and self-assembled structures

— and also includes studies of nanocomposites

and liquid-state properties for microfluidics-based

fabrication and measurement techniques. Physical

properties such as mechanical strength, elastic moduli,

friction, stiction, adhesion, and fatigue strength

are measured, as well as the size of nanoparticles

and the structure and dispersion behavior of

nanoparticulate systems. Other properties such

as electrical conductivity, thermal conductivity,

magnetic properties, electronic properties, and

optical properties are also examined. While the

program focuses on developing measurement

techniques at the nanoscale, proper data interpretation

requires fundamental studies in nanomechanics,

scaling laws, and imaging techniques.

There are currently ten projects under the program:

■ Bridging Length Scales in Theory and Modeling;

■ Electrochemical Processing of Nanoscale Materials;

■ Metrology for Nanoscale Properties;

■ Nanofiller Processing;

■ Nanoindentation;

■ Nanomechanics and Standards;

■ Nanoscale Manufacturing;

■ Nanotribology and Surface Properties;

■ Particle Metrology and Standards; and

■ Physical Properties of Thin Films and Nanostructures.

In many of these individual projects, objectives

are directed toward the study of a particular class of

materials or material properties, but the underlying

theme of the program as a whole is to develop

reliable, accurate measurement techniques for a

broad range of materials and material properties at the

nanoscale. As just one example, four methods for the

determination of the elastic properties of thin films —

atomic force acoustic microscopy, surface acoustic

wave spectroscopy, Brillouin light scattering, and

nanoindentation — are being compared using common

sets of specimens. This study will lead to a better

understanding of the complementary nature of these

techniques for measuring nanostructured materials

and their combined use to determine supplementary

properties such as film thickness or density. Standard

reference materials are being developed in collaboration

with other National Measurement Institutes around the

world for use in the verification of the performance

of these instruments.

Contact: Stephen M. Hsu
40

Nanocharacterization

Process Monitoring of Polymer Clay Nanocomposites

Real-time, on-line measurements of polymer

composite materials properties are desirable

not only because they preempt the need for

post-processing characterization but also because

they can be used to monitor resin conditions, to

detect problems with processing parameters, to

control the process, and to predict performance

of the final product. In this project, we have

developed measurement techniques based on

optical, dielectric, and rheological techniques.

NIST has filled an industry need by designing and

constructing process sensors and by collaborating

with industry partners in the application of new

sensor technology to process monitoring.

Anthony J. Bur

The state of microstructure that forms during the

compounding of polymer and clay nanocomposites

determines their performance properties. On-line,

real-time measurements that are sensitive to

microstructure conformation yield a database that can

improve efficiency and productivity by giving processors

immediate knowledge of the microstructure state.

Real-time measurements can potentially minimize the

extent of off-line microstructure determinations using

x-ray and Transmission Electron Microscopy (TEM)

observations. The on-line instrumentation that we

have developed is a multifunctional device that contains

dielectric, pressure, optical, and ultrasonics sensor ports.

The instrument is designed to attach to the end of a

twin-screw extruder. The resin flow through the sensor

conforms to a slit that is 2 mm high by 28 mm wide,

and the sensors are aligned to interrogate the resin in the

slit region. The extrudate, shown in the picture below,

consists of a strip of material that can be cut into pieces

for off-line measurements.

Nylon 6, when compounded with certain clays

containing polar organo modifiers, can form a

nanocomposite consisting of exfoliated silicate platelets

that are a few nanometers thick by tens of nanometers

in diameter. On the other hand, if the organo modifier

is nonpolar, then the clay particle remains in its

aggregate condition of a micrometer size particulate

when compounded with nylon 6. When the composite

is subjected to an alternating electric field, the

dielectric contrast between particle and resin forms

a resistance–capacitance network that expresses a

dielectric relaxation known as a Maxwell–Wagner

(MW) relaxation. The characteristic relaxation time of

the resin/nano-platelete combination is longer than that

of the resin/aggregate because the nanosize silicate

platelet has a high, effective capacitance.

The table shows characteristic relaxation times and

dielectric relaxation strengths ∆ε for three compounded

nylons: neat, exfoliated clay nanocomposite, and

aggregate clay composite. The measurements were

carried out at processing temperature, 240 oC. After

correcting the data for DC conductivity and electrode

polarization effects, we observed only one dielectric

relaxation in the neat polymer, but two relaxations were

observed in the composites. The single relaxation of

the neat is associated with the α relaxation (log f = 2.40)

of the macromolecule, and the two relaxations of the

composites are the α relaxation (log f = 2.70 and 2.46)

and the MW relaxation at log f = 1.98 and 1.33 for

which the exfoliated microstructure displays the lowest

characteristic frequency. Large ∆ε is characteristic of

MW relaxation.

NY 6/clay NY 6/clay

NY 6 neat aggregate exfoliated

Log f1 2.40 2.70 2.46

Log f2 1.98 1.33

∆ε1 441 1700 2200

∆ε2 18,200 18,400

Contributors and Collaborators

C. Snyder, Y. Lee, N. Noda, S. Roth, V. Prabhu,

P. Start, S. Hudson, J. Obrzut (Polymers Division,

NIST); D. Ho, C. Glinka (NIST Center for Neutron

Research); M. McBrearty (Chemical ElectroPhysics)
41

Nanomanufacturing

In nanoscale manufacturing, knowledge of

inherent and process-induced properties is crucial.

In new realms of nanoscale manufacturing,

nanomaterials will be manufactured in nanoliter

volumes, combining so-called top-down and

bottom-up or self-assembly approaches. Miniature

tools to characterize such materials and processes

are needed. We are developing devices that can

impose a wide variety of process flows and

measure flow-induced properties at transient

and persistent conditions.

Steven Hudson and Frederick Phelan, Jr.

The four-roll mill is a macroscopic flow device

that has played a critical role in elucidating the

interactions between flow and material response. In

the microscale regime, an analogous device is needed

to efficiently characterize fluids. Merely scaling

down the four-roll mill to microscopic dimensions is

inherently problematic due to the rotating components.

Instead, we are developing a device which uses

pressure-generated flow to achieve the same flow

types as a four-roll mill, but is miniaturizable, and has

greater control over the flow. It is also integrable

into high power microscopes and scattering devices.

in the channels. The relative amount of rotation and its

direction can also be adjusted. Figure 2 illustrates the

flow streamlines for conditions that yield extensional

and shear flow.

To evaluate various candidate geometries for a

pressure-driven microchannel device, flow generated

in these devices was calculated in the (Stokes) limit

of low Reynolds number by the finite element method.

Although a variety of geometries produce highly

extensional flow, shear flow is produced at the

stagnation point only when opposing channels are offset

laterally. A suitable geometry is shown in Figure 1.

A wide range of flow type, including pure shear, is

possible in this device by adjusting the relative flow rate

Figure 1: a) Design of a microchannel analog of the 4-roll mill.

b) Flow type as a function of pressure ratio p1/p2. Flow type

values equal to –1, 0, and 1 correspond to pure rotation, shear

and extension, respectively.

Figure 2: 2D Stokes calculations of pressure-driven flow in

microchannels. Streamlines are shown for a) extensional and

b) shear flow conditions.

Figure 3: Images of drops in a computer-controlled

cross-channel extensional flow device. Image analysis control

feedback adjusts the flow to keep the drop(s) at the stable

stagnation point of the device during deformation (shown at left)

and collision experiments (series at right).

A computer control system, with image analysis

feedback, has been developed. Experiments with

immiscible polymeric fluids have demonstrated that, by

using this device, drops can be moved into the device,

placed at the stagnation point, deformed, and broken

(Figure 3). Drops were then caused to collide and

coalesce. Surface tension-driven relaxation of drop

deformation has been measured. Based on these

results, a focused project to measure interfacial tension,

with partner companies in the NIST Combinatorial

Methods Center (NCMC), was established.

Contributors and Collaborators

J.T. Cabral, J.A. Pathak (Polymers Division, NIST);

NIST Combinatorial Methods Center Focused Project

(with member companies) to measure interfacial tension.

Nanocharacterization
42
43

Polymers Division FY03 Annual Report Publication List

Polymers Division FY03 Annual Report Publication List

Characterization and Measurement —

Internal Capabilities/Method Development

Polymer Crystallization

J.F. Douglas, V. Ferreiro, J. Warren, and A. Karim,

“Observation of Growth Pulsations in Polymer

Dendritic Crystallization in PEO/PMMA Blend Films,”

ACS Polymer Preprints 43, 862–863 (2002).

V. Ferreiro, J.F. Douglas, J. Warren, and A. Karim,

“Non-Equilibrium Pattern Formation in the

Crystallization of Polymer Blend Films,” Physical

Review E 65, 042802:1–4 (2002).

V. Ferreiro, J.F. Douglas, J.A. Warren, and

A. Karim, “Growth Pulsations in Symmetric Dendritic

Crystallization in Thin Polymer Blend Films,” Physical

Review E 65, 051606:1–16 (2002).

D.L. VanderHart and C.R. Snyder, “Proton NMR

Characterization of Room-Temperature Aging after

Modest Thermal Cycling in Isotactic Polypropylene,”

Macromolecules 36, 4813–4826 (2003).

D.L. VanderHart, C.R. Snyder, and R.G. Alamo,

“Proton NMR Characterization of Room-Temperature

Aging in Isotactic polypropylene and Ethylene-Octene

Copolymers,” ACS Polymer Preprints 44, 285–286

(2003).

Gelation, Diffusion, and the Glass Transition

D. Bedrov, G.D. Smith, and J.F. Douglas, “Influence

of Self-Assembly on Dynamical and Viscoelastic

Properties of Telechelic Polymer Solutions,”

Europhysics Letters 59, 384–390 (2002).

J.F. Douglas, M.S. Kent, S.K. Satija, and A. Karim,

“Polymer Brushes: Structure and Dynamics,” in

Encyclopedia of Materials: Science and Technology,

(in press).

S.C. Glotzer, Y. Gebremichael, N. Lacevic,

T.B. Schroder, and F.W. Starr, “Spatially Heterogeneous

Dynamics in Liquids Near Their Glass Transition,” in

ACS Symposium Series, (Washington, D.C.: American

Chemical Society, 2002) pp. 214 –227.

 N. Lacevic, F.W. Starr, T.B. Schroder,

V.N. Novikov, and S.C. Glotzer, “Growing Correlation

Length on Cooling Below the Onset of Caging in a

Simulated Glass-Forming Liquid,” Physical Review E

66, art. no. 030101 (2002).

S. Lin–Gibson, H.J. Walls, S.B. Kennedy, and

E.R. Welsh, “Chitosan Hydrogels: Crosslink Kinetics

and Gel Properties,” ACS Polymeric Materials: Science

and Engineering 88, 199–200 (2003).

P.A. Netz, F.W. Starr, M.C. Barbosa, and

H.E. Stanley, “Relation between Structural and

Dynamical Anomalies in Supercooled Water,”

Physica A 314, 470–476 (2002).

H.E. Stanley, S.V. Buldyrev, N. Giovambattista,

E. La Nave, S. Mossa, A. Scala, F. Sciortino,

F.W. Starr, and M. Yamada, “Application of Statistical

Physics to Understand Static and Dynamic Anomalies

in Liquid Water,” Journal of Statistical Physics 110,

1039–1054 (2003).

F.W. Starr, C.A. Angell, and H.E. Stanley,

“Prediction of Entropy and Dynamic Properties

of Water below the Homogeneous Nucleation

Temperature,” Physica A — Statistical Mechanics

And Its Applications 323, 51–66 (2003).

F.W. Starr, S. Sastry, J.F. Douglas, and

S.C. Glotzer, “What Do We Learn from the Local

Geometry of Glass-Forming Liquids?” Physical Review

Letters 89, 5501–5505 (2002).

Nanoscale Science, Engineering and Technology

R.D. Davis, J.W. Gilman, and D.L. VanderHart,

“Processing Degradation of Polyamide 6/Montmorillonite

Clay Nanocomposites and Clay Organic Modifier,”

Polymer Degradation and Stability 79, 111–121 (2003).

R.C. Hedden and B.J. Bauer, “Structure and

Dimensions of PAMAM/PEG Dendrimer-Star

Polymers,” Macromolecules 36, 1829–1835 (2003).

R.C. Hedden, B.J. Bauer, A.P. Smith, F. Gröhn, and

E.J. Amis, “Templating of Inorganic Nanoparticles by

PAMAM/PEG Dendrimer-Star Polymers,” Polymer 43,

5473–5481 (2002).

G.A. Holmes, E. Feresenbet, and D. Raghavan,

“Using Self-Assembled Monolayer Technology to Probe

the Mechanical Response of the Fiber Interphase-Matrix

Interphase Interface,” Composite Interfaces, (in press).

G.A. Holmes, J.H. Kim, C.K. Moon, and

W.G. McDonough, “Coordinated Fracture and Failure

Initiation in Microcomposites,” in ICCE-10, July 2003,

New Orleans, LA, (in press).
44

Polymers Division FY03 Annual Report Publication List

U.S. Jeng, T.L. Lin, L.Y. Wang, L.Y. Chiang,

D.L. Ho, and C.C. Han, “SANS Structural

Characterization of Fullerenol-Derived Star Polymers

in Solutions,” Applied Physics A — Materials Science

& Processing 74, S487–S489 (2002).

T. Kashiwagi, A.B. Morgan, J.M. Antonucci,

M.R. VanLandingham, R.H. Harris, W.H. Awad, and

J.R. Shields, “Thermal and Flammability Properties of a

Silica–Poly(methylmethacrylate) Nanocomposite,”

Journal of Applied Polymer Science 89, 2072–2078

(2003).

J.S. Melinger, V.D. Kleiman, D. McMorrow,

F. Gröhn, B.J. Bauer, and E.J. Amis, “Ultrafast

Dynamics of Gold-Based Nanocomposite Materials,”

Journal of Physical Chemistry A 107, 3424–3431

(2003).

V. Percec, A.E. Dulcey, Y. Miura, U. Edlund,

V.S.K. Balagurusamy, S.D. Hudson, H. Duan, and

P.A. Heiney, “Solvophobically Driven Self-Assembly

of Chiral Supramolecular Dendrimers,” ACS Polymer

Preprints 43, 458–459 (2002).

V. Percec, M. Glodde, T.K. Bera, Y. Miura,

I. Shiyanovskaya, K.D. Singer, V.S.K. Balagurusamy,

P.A. Heiney, I. Schnell, A. Rapp, H.W. Spiess,

S.D. Hudson, and H. Duan, “Self-Organization of

Supramolecular Helical Dendrimers Into Complex

Electronic Materials,” Nature 419, 384–387 (2002).

D. Raghavan, E. Feresenbet, D. Yebassa,

A. Emekalam, and G. Holmes, “Dispersion of

Functionalized Nanoclay Platelests in an Amine-Cured

Epoxy Resin System,” in Materials Research Society

Symposium Proceedings, 703, v9.26.1–v9.26.8,

November 2001, Boston, MA.

Polymer Blends

C.C. Han, H. Wang, K. Shimizu, H. Kim,

E. Hobbie, and Z.G. Wang, “Structure Development

from Simultaneous Phase Separation and Crystallization

of Metallocene Polyolefin Blends,” ACS Polymer

Preprints 43, 856–857 (2002).

E.K. Hobbie, H.S. Jeon, H. Wang, H. Kim,

D.J. Stout, and C.C. Han, “Shear-Induced Structure

in Polymer Blends With Viscoelastic Asymmetry,”

Journal of Chemical Physics 117, 6350–6359 (2002).

A. Karim, A. Sehgal, E.J. Amis, and J.C. Meredith,

“Combinatorial Mapping of Polymer Blends Phase

Behavior,” in Experimental Design for Combinatorial

and High Throughput Materials Science, edited by

J.N. Cawse (Hoboken, NJ: John Wiley & Sons, Ltd.,

2003) Chap. 5, pp. 73–88.

A. Karim, K. Yurekli, C. Meredith, E. Amis, and

R. Krishnamoorti, “Combinatorial Methods for Polymer

Materials Science: Phase Behavior of Nanocomposite

Blend Films,” Polymer Engineering and Science 42,

1836–1840 (2002).

F.A. Landis, R.B. Moore, K.A. Page, and C.C. Han,

“SAXS Analysis of the Thermal Relaxation Behavior of

Oriented Perfluorosulfonate Ionomer Membranes,”

ACS Polymeric Materials: Science and Engineering

87, 121–122 (2002).

G. Matsuba, K. Shimizu, H. Wang, Z.G. Wang, and

C.C. Han, “Correlation Between Phase Separation

and Crystallization in Poly(ethylene-co-hexene) and

Poly(ethylene-co-octene),” ACS Polymeric Materials:

Science and Engineering 87, 317–318 (2002).

J. Parkas, M. Paulsson, D.L. VanderHart, and

U. Westermark, “Accelerated Light-Induced Aging

of Alpha-, Beta-, and Gamma-C-13-Enriched Cell

Wall-Dehydrogenation Polymers Studied With Solid

State C-13 NMR Spectroscopy,” Journal of Wood

Chemistry and Technology 22, 199–218 (2002).

K. Shimizu, H. Wang, Z. Wang, H. Kim, and

C.C. Han, “Morphological Development in Copolymer

Blends of Poly(ethylene-co-hexene) and Poly(ethyleneco-butene),” ACS Polymer Preprints 43, 273–274

(2002).

K. Shimizu, H. Wang, Z.G. Wang, G. Matsuba,

and C.C. Han, “Phase Behavior in Polyolefin Blend,”

ACS Polymeric Materials: Science and Engineering

87, 319–320 (2002).

L.P. Sung, J.F. Douglas, C.C. Han, and A. Karim,

“Suppression of Phase Separation Pattern Formation

in Blend Films with Block Copolymer Compatibilizer,”

Journal of Polymer Science Part B-Polymer Physics 41,

1697–1700 (2003).

R.T. Tucker, C.C. Han, A.V. Dobrynin, and

R.A. Weiss, “Small-angle Neutron Scattering Analysis

of Blends with Very Strong Intermolecular Interactions:

Polyamide/ionomer Blends,” Macromolecules 36,

4404–4410 (2003).

Z. Wang, E. Balizer, B. Hsiao, and C.C. Han,

“Structure Evolution During Ferroelectric Phase

Transition in a Vinylidene Fluoride/Trifluoroethylene

Copolymer,” ACS Polymeric Materials: Science and

Engineering 43, 203–204 (2002).

Z. Wang, H. Wang, B.S. Hsiao, D. Gersappe, and

C.C. Han, “In-situ Small Angle X-ray Scattering of

Crystallization in Poly(ethylene/hexene) Copolymer

Subjected to Step Shear,” ACS Polymer Preprints 43,

271–272 (2002).
45

Polymers Division FY03 Annual Report Publication List

Polymer Composites

M.Y.M. Chiang and M. Fernandez–Garcia, “Relation

of Swelling and Tg Depression to the Apparent Free

Volume of a Particle-Filled Epoxy-based Adhesive,”

Journal of Applied Polymer Science, (in press).

M.Y.M. Chiang and J. He, “An Analytical

Assessment of Using the Iosipescu Shear Test for

Hybrid Composites,” Composite Part B: Engineering

33, 461–470 (2002).

M.Y.M. Chiang, C.R. Schultheisz, and J. He,

“The Effects of Local Inhomogeneity on Shear

Property Measurements of Hybrid Composites,”

in SAMPE 2002 — Winter Technical Meeting,

November 2002, Baltimore, MD.

E. Feresenbet, D. Raghavan, and G.A. Holmes,

“Application of Self Assembled Technology to Probe

Fiber-Matrix Adhesion,” in Materials Research Society

Symposium Proceedings, November 2001, Boston, MA.

E. Feresenbet, G.A. Holmes, and D. Raghavan,

“The Influence of Silane Coupling Agent Composition

on the Surface Characterization of Fiber and on

Fiber-Matrix Interfacial Shear Strength,” Journal of

Adhesion 79, 643–665 (2003).

J. He, M.Y. Chiang, D.L. Hunston, and C.C. Han,

“Application of the V-notch Shear Test for

Unidirectional Hybrid Composites,” Journal of

Composite Materials 36, 2653–2666 (2002).

J. He, M.Y.M. Chiang, W.G. McDonough, and

D.L. Hunston, “Experimental and Theoretical

Evaluations of the Iosipescu Shear Test for Hybrid

Fiber Composites,” in SAMPE 2002, 154–164,

May 2002, Long Beach, CA.

G.A. Holmes and W.G. McDonough,

“E-Glass/DGEBA/m-PDA Model Composites:

Time Dependent Failure in a Brittle Multi-Fiber

Composite,” 47th International SAMPE Symposium

and Exhibition 2002, 47:2/2, 1690–1702.

G.A. Holmes, R.C. Peterson, D.L. Hunston, and

W.G. McDonough, “E-Glass/DGEBA/m-PDA Single

Fiber Composites: Interface Debonding During Fiber

Fracture,” Polymer Composites, (in press).

D.L. Hunston and W.G. McDonough, “Stiffness

and Failure Behavior of Model Hybrid Composites,”

in Proceedings of the American Society for Composites

Seventeenth Technical Conference, October 2002,

West Lafayette, IN.

D.L. Hunston, Z. Miyagi, C.R. Schultheisz,

S. Zaghi, and H. Binson, “Sandwich Bending Specimen

for Characterizing Adhesive Properties,” Mechanics of

Time-Dependent Materials, (in press).

J.L. Lenhart, J.H. van Zanten, J.P. Dunkers, and

R.S. Parnas, “Using a Localized Fluorescent Dye to

Probe the Glass/Resin Interphase,” Polymer Composites

23, 555–563 (2002).

J.L. Lenhart, J.H. van Zanten, J.P. Dunkers, and

R.S. Parnas, “Characterization of Sizing Layers and

Buried Polymer/Sizing/Substrate Interfacial Regions

Using a Localized Fluorescent Probe,” Journal of

Colloid and Interface Science 257, 398–407 (2003).

S. Lin–Gibson, G. Schmidt, H. Kim, C.C. Han,

and E.K. Hobbie, “Shear-Induced Mesostructure in

Nanoplatelet-Polymer Gels,” Journal of Chemical

Physics, (in press).

S. Lin–Gibson and J.S. Riffle, “Chemistry and

Properties of Phenolic Resins and Networks,” in

Synthetic Methods in Step-Growth Polymers, edited by

M.E. Rogers and T.E. Long (New York: John Wiley &

Sons, Inc., 2003) Chap. 7, pp. 369–423.

D. Raghavan, J. He, D.L. Hunston, and D. Hoffman,

“Strain Rate Dependence of Fracture in a RubberToughened Epoxy System,” Journal of Adhesion 78,

723–739 (2002).

M.J. Rich, L.T. Drzal, D.L. Hunston, G.A. Holmes,

and W.G. McDonough, “Round Robin Assessment of

the Single Fiber Fragmentation Test,” in Proceedings of

the American Society for Composites 17th Technical

Conference, 1–9 October 2002, West Lafayette, IN.

J. Toke, J.D. Muzzy, and M.T. Cicerone,

“Using LSM to Investigate Maleated Polypropylene in

Polypropylene/Glass Bead Composites,” in Proceedings

of the Annual Technical Meeting of the Society of Plastics

Engineers, 2127–2130, May 2003, Nashville, TN.

D.L. Woerdeman, W. Ou, J.L. Lenhart, and

R.S. Parnas, “Interpreting The Signal From A Localized

Fluorescence Sensor: A Study By Angle-Resolved XPS

And Dynamic SIMS,” Journal of Colloid and Interface

Science 262, 594–602 (2003).

Sum Frequency Generation Spectroscopy

K. Efimenko, W.E. Wallace, and J. Genzer, “Surface

Modification of Sylgard-184 Poly(dimethyl siloxane)

Networks by Ultraviolet and Ultraviolet/Ozone

Treatment,” Journal of Colloid and Interface Science

254, 6–315 (2002).

P.T. Wilson, K.A. Briggman, J.C. Stephenson,

W.E. Wallace, and L.J. Richter, “Molecular Order at

Polymer Interfaces Measured by Broad-Bandwidth

Vibrationally-Resolved Sum-Frequency Generation

Spectroscopy,” in Quantum Electronics and Laser

Science Conference (QELS 2001), 57, 189, (2001).
46

P.T. Wilson, L.J. Richter, W.E. Wallace,

K.A. Briggman, and J.C. Stephenson, “Correlation

of Molecular Orientation with Adhesion at

Polystyrene/Solid Interfaces,” Chemical Physics

Letters 363, 161–168 (2002).

P.T. Wilson, L.J. Richter, W.E. Wallace,

K.A. Briggman, and J.C. Stephenson, “Correlation

of Molecular Orientation With Adhesion at

Polystyrene/Solid Interfaces,” Chemical Physics

Letters 363, 161–168 (2002).

Characterization and Measurement —

Standards and Data

Polymer Standards

B.M. Fanconi, J.A. Tesk, and W.F. Guthrie,

“Reference Material 8457, Ultra High Molecular Weight

Polyethylene 0.5 cm Cubes,” in Society of Biomaterials

29th Annual Meeting Transactions, 587, April 2003,

Reno, NV.

C.M. Guttman and W.R. Blair, “Recertification of

SRM 1483a, a Polyethylene,” NIST SP, (in press).

C.M. Guttman, W.R. Blair, B.M. Fanconi,

R.J. Goldschmidt, S.J. Wetzel, and D.L. VanderHart,

“Certification of a Polystyrene Synthetic Polymer,

SRM 2888,” NIST SP 260–152, (in press).

J.M. Maurey, K.M. Flynn, and C.M. Guttman,

“Certification of Standard Reference Material 1474a,

A Polyethylene Resin,” NIST SP 260–148 (2003).

J.A. Tesk, “Reference Materials for Tissue

Engineered Medical Products,” in Tissue Engineering,

(in press).

Mass Spectrometry

B.J. Bauer and K.M. Flynn, “MALDI of Structured

Polymer Particles,” in Proc. of the 51st ASMS

Conference on Mass Spectrometry and Allied Topics,

June 2003, Montreal, Canada, (in press).

H.C.M. Byrd, C.M. Guttman, and D.P. Ridge,

“Molecular Mass Determination of Saturated

Hydrocarbons: Reactivity of η5- Cyclopentadienylcobalt

Ion (CpCo+) and Linear Alkanes up to C-30,” Journal

of the American Society for Mass Spectrometry 14,

51–57 (2003).

H.C.M. Byrd, S. Lin–Gibson, S. Bencherif,

D.L. VanderHart, K.L. Beers, B.J. Bauer, B.M. Fanconi,

C.M. Guttman, and W.E. Wallace, “MALDI-TOF MS

Characterization of Covalently-Cationized Polymers,”

ACS Polymeric Materials: Science and Engineering

88, 80–81 (2003).

J.E. Girard, M. Konaklieva, J. Gu, C.M. Guttman,

and S.J. Wetzel, “Characterization of Linear and

Branched Polyethylenimine (PEI) by ESI-MS and

MALDI-TOF-MS,” in Proc. of the 51st ASMS

Conference on Mass Spectrometry and Allied Products,

June 2003, Montreal, Canada, (in press).

C.M. Guttman, “Mass Spectrometry,” Encyclopedia

of Polymer Science and Technology, (New York: John

Wiley & Sons, Inc., 2002).

C.M. Guttman, B.J. Bauer, K.L. Beers,

S.A. Bencherif, H.C.M. Byrd, and S. Lin–Gibson,

“MALDI-TOF MS Analysis of Chain-End

Functionalized Polymers,” in Proc. of the 51st ASMS

Conference on Mass Spectrometry and Allied Topics,

June 2003, Montreal, Canada, (in press).

A.J. Kearsley, W.E. Wallace, J. Bernal, and

C.M. Guttman, “Automated Peak Picking and

Integration Algorithm for Mass Spectral Data,” in Proc.

of the 51st ASMS Conference on Mass Spectrometry and

Allied Topics, June 2003, Montreal, Canada, (in press).

S. Lin–Gibson, S. Bencherif, K.L. Beers, and

H.C.M. Byrd, “MALDI-TOF-Mass Spectral

Characterization of Covalently Cationized Polystyrene,”

Macromolecules 36, 4669–4671 (2003).

S. Lin–Gibson, L. Brunner, D.L. VanderHart,

B.J. Bauer, B.M. Fanconi, C.M. Guttman, and

W.E. Wallace, “MALDI MS Characterization of

Cationized Covalent Polyethylene,” ACS Polymer

Preprints 43, 1331–1332 (2002).

S. Lin–Gibson, L. Brunner, D.L. VanderHart,

B.J. Bauer, B.M. Fanconi, C.M. Guttman, and

W.E. Wallace, “Optimizing the Covalent Cationization

Method for the Mass Spectrometry of Polyolefins,”

Macromolecules 35, 7149–7156 (2002).

M.R. Nyden, W.E. Wallace, and W.H. Awad,

“An Application of MALDI-MS and Reactive Molecular

Dynamics in Determining the Mechanisms of

Char-Formation During the Thermal and Oxidative

Degradation of Polymers,” in ACS Polymeric Materials:

Science and Engineering, 88, 178–179, March 2003,

New Orleans, LA.

W.E. Wallace and D.A. Fischer, “Resonant Soft

X-ray Photofragmentation of Propane,” Journal of

Electron Spectroscopy and Related Phenomena 130,

1–6 (2003).

W.E. Wallace, C.M. Guttman, and S.D. Hanton,

“Quantitative Synthetic Polymer Mass Spectrometry

Workshop,” Journal of Research of the National

Institute of Standards and Technology 108, 79–85

(2003).

Polymers Division FY03 Annual Report Publication List
47

S.J. Wetzel, C.M. Guttman, and J.E. Girard,

“The Influence of Laser Energy and Matrix of MALDI

on the Molecular Mass Distribution of Poly(ethylene

glycol),” in ACS Polymeric Materials: Science and

Engineering 88, 74–75 (2003).

S.J. Wetzel, C.M. Guttman, and J.E. Girard,

“A Study of the Effects of Matrix and Laser Energy

on the Molecular Mass Distribution of Synthetic

Polymers,” in Proceedings of the 51st ASMA

Conference on Mass Spectrometry and Allied Products,

June 2003, Montreal, Canada, (in press).

T. Yalcin, W.E. Wallace, C.M. Guttman, and L. Li,

“Metal Powder Substrate Assisted Laser Desorption

Mass Spectrometry for Polyethylene Analysis,”

Analytical Chemistry 74, 4750–4756 (2002).

Electronics Materials

Polymers for Lithography

R.L. Jones, T. Hu, E.K. Lin, W.L. Wu, D.M. Casa,

N.G. Orji, T.V. Vorburger, P.J. Bolton, and G.G. Barclay,

“Sub-nanometer Wavelength Metrology of Lithographically

Prepared Structures: A Comparison of Neutron and

X-ray Scattering,” in Proceedings of the SPIE: Metrology,

Inspection, and Process Control for Microlithography

XVII, February 2003, Santa Clara, CA.

R.L. Jones, T.J. Hu, V.M. Prabhu, C.L. Soles,

E.K. Lin, W.L. Wu, D.L. Goldfarb, and M. Angelopoulos,

“Form of Deprotection in Chemically Amplified

Resists,” in Proceedings of the International Conference

on Characterization and Metrology for ULSI

Technology, March 2003, Austin, TX, (in press).

R.L. Jones, T.J. Hu, V.M. Prabhu, C.L. Soles,

E.K. Lin, W.L. Wu, D.L. Goldfarb, M. Angelopoulos,

B.C. Trinque, and C.G. Willson, “Deprotection

Volume Characteristics and Line Edge Morphology

in Chemically Amplified Resists,” in Proceedings of

the SPIE: Advances in Resist Technology and

Processing XX, 5039, 1031, March 2003, Austin, TX.

R.L. Jones, V.M. Prabhu, D.L. Goldfarb, E.K. Lin,

C.L. Soles, J.L. Lenhart, W.L. Wu, and M. Angelopoulos,

“Correlation of the Reaction Front with Roughness in

Chemically Amplified Photoresists,” in Symposia of the

American Chemical Society, (Washington, D.C.:

American Chemical Society), (in press).

J.L. Lenhart, R.L. Jones, E.K. Lin, C.L. Soles,

W.L. Wu, D.A. Fischer, S. Sambasivan, D.L. Goldfarb,

and M. Angelopoulos, “Probing Surface and Bulk

Chemistry in Resist Films Using Near Edge X-Ray

Absorption Fine Structure,” Journal of Vacuum Science

& Technology B 20, 2920–2926 (2002).

V.M. Prabhu, R.L. Jones, E.K. Lin, C.L. Soles,

W.L. Wu, D.L. Goldfarb, and M. Angelopoulos,

“Polyelectrolyte Effects in Model Photoresis Developer

Solutions: Roles of Base Concentration and Added

Salts,” in Proceedings of the SPIE, Advances in

Resist Technology and Processing XX, 5039, 404,

February 2003, Santa Clara, CA.

V.M. Prabhu, R.L. Jones, E.K. Lin, and W.L. Wu,

“Polyelectrolyte Effects in Model Photoresist Developer

Solutions,” Journal of Vacuum Science and Technology

B 21, 1403–1410 (2003).

C.L. Soles, J.F. Douglas, E.K. Lin, J.L. Lenhart,

R.L. Jones, W.L. Wu, D. Goldfarb, and M. Angelopoulos,

“Incoherent Neutron Scattering and the Dynamics of

Thin Film Photoresist Polymers,” Journal of Applied

Physics 93, 1978–1986 (2003).

Porous Low-k Dielectric Thin Films

B.J. Bauer, H.J. Lee, R.C. Hedden, C.L. Soles,

D.W. Liu, and W.L. Wu, “SANS Characterization

of Nanoporous Thin Films for the Next Generation

of Integrated Circuits,” ACNS WEBsite:

http://www.sns.gov/acns/, June 2002, Knoxville, TN.

R.C. Hedden, H.J. Lee, B.J. Bauer, C.L. Soles,

W.L. Wu, and E.K. Lin, “Measurement of Pore Size and

Matrix Characteristics in Low-k Dielectrics by Neutron

Contrast Variation,” in Proceedings of the International

Conference on Characterization and Metrology for

ULSI Technology, March 2003, Austin, TX.

H.J. Kim, W.L. Wu, B.J. Bauer, E.K. Lin, J.Y. Kim,

Y.H. Kim, and H.J. Lee, “Structural Characterization

of Porous Low-k SiOC Thin Films Using X-Ray

Porosimetry,” in IEEE International Conference on

Interconnect Technology, 54–56, 2002.

H.J. Lee, E.K. Lin, B.J. Bauer, W.L. Wu,

B.K. Hwang, and W.D. Gray, “Characterization of

Chemical-Vapor-Deposited Low-K Thin Films Using

X-Ray Porosimetry,” Applied Physics Letters 82,

1084–1086 (2003).

H.J. Lee, C.L. Soles, D.W. Liu, B.J. Bauer,

and W.L. Wu, “Pore Size Distributions in Low-k

Dielectric Thin Films from X-ray Porosimetry,”

Journal of Polymer Science Part B — Polymer Physics

40, 2170–2177 (2002).

E.K. Lin, H.J. Lee, B.J. Bauer, H. Wang, J.T. Wetzel,

and W.L. Wu, “Structure and Property Characterization

of Low-k Dielectric Porous Thin Films Determined by

X-ray Reflectivity and Small-angle Neutron Scattering,”

in Low Dielectric Constant Materials for IC Applications,

edited by P.S. Ho, J. Leu, and W.W. Lee (Springer

Publishing, Inc.), (in press).

Polymers Division FY03 Annual Report Publication List
48

Dielectric Characterization / Electronic Packaging

E. Balizer, F.B. Bateman, A.S. DeReggi, and

D.A. Neumann, “Electrostriction Mechanism in

Electro-Irradiated Ferroelectric Copolymer:

a Frequency Response Model,” in 2000 Conference

on Electrical Insulation and Dielectric Phenomena,

191–194.

T. Bergstresser, R. Hilburn, J. Obrzut, and

K. Phillips, “Embedded Capacitance Materials and

Their Application in High Speed Design,” in IPC Expo

Technical Conference, S06: 3.1–3.8, March 2003,

Long Beach, CA.

C.K. Chiang, “The Bromine Doping of

Polyacetylene,” Physica 321, 139–151 (2003).

C.K. Chiang and R. Popielarz, “Polymer Composites

With High Dielectric Constant,” Ferroelectrics 275,

1–9 (2002).

D. Josell, W.E. Wallace, J.A. Warren, D. Wheeler,

and A.C. Powell, “Misaligned Flip-Chip Solder Joints:

Prediction and Experimental Determination of

Force-Displacement Curves,” Journal of Electronic

Packaging 124, 227–233 (2002).

J. Obrzut and A. Anopchenko, “Numerical Analysis

of a Coaxial Line Terminated with a Complex Gap

Capacitance,” in IEEE Conference on Instrumentation

and Measurements, 1074–1077, May 2003, Vail, CO.

W. Sakai and C.K. Chiang, “Dielectric Properties

of Multi-layer High-k Composite Films,” in Materials

Research Society Symposium Proceedings, 710,

DD6.17.1–5, November 2002, Boston, MA.

Polymer Thin Film Fundamentals

E.Q. Chen, Y. Xia, M.J. Graham, M.D. Foster,

Y.L. Mi, W.L. Wu, and S.Z.D. Cheng, “Glass Transition

Behavior of Polystyrene Blocks in the Cores of Collapsed

Dry Micelles Tethered by Poly(Dimethylsiloxane)

Coronae in a PS-B-PDMS Diblock Copolymer,”

Chemistry of Materials 15, 2129–2135 (2003).

C.K. Chiang and W. Sakai, “Application of a

Buffer Layer for the Dielectric Measurement of

Thin Polymer Films,” in Materials Research

Society Symposium Proceedings, 699, R7.1.1–4,

November 2002, Boston, MA.

R.L. Jones, C.L. Soles, F.W. Starr, E.K. Lin,

J.L. Lenhart, W.L. Wu, D.L. Goldfarb, and

M. Angelopolous, “Chain Conformation in Ultrathin

Polymer Films,” in Proceedings of the SPIE: Advances

in Resist Technology and Processing XIX, 4690,

342–350, March 2002, Santa Clara, CA.

J.L. Lenhart and W.L. Wu, “Influence of Cross-link

Density on the Thermal Properties of Thin Polymer

Network Films,” Langmuir 19, 4863–4865 (2003).

C.L. Soles, J.F. Douglas, W.L. Wu, and

R.M. Dimeo, “Incoherent Neutron Scattering as a

Probe of the Dynamics in Molecularly Thin Polymer

Films,” Macromolecules 36, 373–379 (2003).

C.L. Soles, J.F. Douglas, W.L. Wu, H. Peng, and

D.W. Gidley, “A Broad Perspective on the Dynamics of

Highly Confined Polymer Films,” in Materials Research

Society Symposium Proceedings, 2002.

B.D. Vogt, C.L. Soles, H.J. Lee, E.K. Lin,

and W.L. Wu, “Confinement Effects on Moisture

Absorption Kinetics in Polyelectrolyte Films,” in

ACS Polymeric Materials: Science and Engineering,

September 2003, New York, NY, (in press).

C.Y. Wang, V.M. Prabhu, C.L. Soles, B.D. Vogt,

W.L. Wu, E.K. Lin, and S.K. Satija, “Interdiffusion

in Polystyrene and End-Functional Polystyrene

Thin Films near a Solid Surface,” in ACS Polymeric

Materials: Science and Engineering, New York, NY,

September 2003, (in press).

C.C. White, W.L. Wu, Y. Pu, M. Rafailovich, and

J. Sokolov, “Probe Segregation and Tg Determination

of a Supported Ultra-Thin Polystyrene Film Studied by

X-ray and Neutron Reflectivity, and SIMS,” Polymer

Engineering and Science 43, 1241–1249 (2003).

Biomaterials

Tissue Engineeering Metrology

O.L. Bailey, N.R. Washburn, and F.W. Wang,

“The Use of Real-Time Polymerase Chain Reaction in

Quantifying Inflammatory Responses to Biomaterials,”

in Society of Biomaterials 29th Annual Meeting

Transactions, 513, April 2003, Reno, NV.

S.B. Kennedy, Y. Mei, R. Gross, N.R. Washburn,

and E.J. Amis, “Quantifying Cell-Response to

Materials Through Population Analyses Enabled

by High-Throughput Techniques,” in Society of

Biomaterials 29th Annual Meeting Transactions, 26,

April 2003, Reno, NV.

C.A. Khatri and F.W. Wang, “Controlled Release of

Transforming Growth Factor from Composite Bone

Grafts Consisting of Calcium Phosphate Cement and

Biodegradable Particulates,” in Society of Biomaterials

29th Annual Meeting Transactions, 476, April 2003,

Reno, NV.

Polymers Division FY03 Annual Report Publication List
49

F.W. Wang, C.A. Khatri, J.F. Hsii, S. Hirayama, and

S. Takagi, “Polymer-Filled Calcium Phosphate Cement:

Mechanical Properties and Controlled Release of

Growth Factor,” in Biomedical Engineering: Recent

Developments, edited by J. Vossoughi, (in press).

N.R. Washburn, S.B. Kennedy, C.G. Simon,

K.M. Yamada, and E.J. Amis, “High-Throughput

Investigation of Cell Proliferation on Crystalline

Polymers,” in Society of Biomaterials 29th Annual

Meeting Transactions, 528, April 2003, Reno, NV.

S. Yoneda, W.F. Guthrie, D.S. Bright, C.A. Khatri,

and F.W. Wang, “Effects of Hydrolytic Degradation

on in Vitro Biocompatibility of Poly(D,L-Lactic Acid),”

in IADR/AADR/CADR 80th General Session, 1364,

March 2002, San Diego, CA.

Dental Materials

J.M. Antonucci, S. Dickens, B.O. Fowler,

H.H.K. Xu, and W.G. McDonough, “Chemistry of

Silanes: Interfaces in Dental Polymers and Composites,”

in Proceedings of the Academy of Dental Materials

Annual Meeting, October 2003, Charleston, SC,

(in press).

J.M. Antonucci, B.O. Fowler, S.H. Dickens,

and N.D. Richards, “Novel Dental Resins from

Trialkoxysilanes and Dental Monomers by in-situ

Formation of Oligomeric Silyl Ethers and Silsesquioxanes,”

ACS Polymer Preprints 43, 633–634 (2002).

J.M. Antonucci, W.G. McDonough, D.W. Liu, and

D. Skrtic, “Effect of Polymer Matrices on Methacrylate

Conversion and Mechanical Strength of Bioactic

Composites Based on Amorphous Calcium Phosphate,”

ACS Polymer Preprints 43, 741–742 (2002).

J.M. Antonucci, W.G. McDonough, D.W. Liu,

and D. Skrtic, “Effect of Acidic Comonomers on

Methacrylate Conversion and Mechancial Strength of

Bioactive Composites Based on Amorphous Calcium

Phosphate,” ACS Polymeric Materials: Science and

Engineering 88, 50–51 (2003).

S.H. Dickens, J.M. Antonucci, and B.O. Fowler,

“Evaluation of the Interactions of a Silane Agent with

Dental Monomers by Near Infrared Spectroscopy,”

ACS Polymer Preprints 43, 747–748 (2002).

C.C. Khatri, J.W. Stansbury, C.R. Schultheisz,

and J.M. Antonucci, “Synthesis, Characterization and

Evaluation of Urethane Derivatives of Bis-GMA,”

Dental Materials, (in press).

W.G. McDonough, J.M. Antonucci, J.P. Dunkers,

and G.E. Schumacher, “Glass-fiber/resin Interfacial

Strength: The Microbond Test and Chemical Evaluation,”

in Proceedings of the Academy of Dental Materials

Annual meeting, October 2003, Charleston, SC,

(in press).

D. Skrtic and J.M. Antonucci, “Effect of

Bifunctional Co-monomers on Mechanical Strength and

Water Sorption of Amorphous Calcium Phosphate and

Silanized Glass-filled Bis-GMA-based Composites,”

Biomaterials 24, 2881–2888 (2003).

D. Skrtic, J.M. Antonucci, and E.D. Eanes,

“Amorphous Calcium Phosphate-Based Bioactive

Polymeric Composites for Mineralized Tissue

Regeneration,” Journal of Research of the National

Institute of Standards and Technology 108, 167–182

(2003).

D. Skrtic, J.W. Stansbury, and J.M. Antonucci,

“Volumetric Contraction and Methacrylate

Conversion in Photopolymerized Amorphous

Calcium Phosphate/Methacrylate Composites,”

Biomaterials 24, 2443–2449 (2003).

M.D. Weir, N.D. Richards, and J.M. Antonucci,

“Structural Effects of Experimental Comonomers on

Conversion and Polymerization Shrinkage of Dental

Composites,” in Society for Biomaterials 29th Annual

Meeting Transactions, 543, April 2003, Reno, NV.

H.H.K. Xu, F.C. Eichmiller, D.T. Smith,

G.E. Schumacher, A.A. Giuseppetti, and J.M. Antonucci,

“Effect of Thermal Cycling on Whisker-Reinforced

Dental Resin Composites,” Journal of Materials

Science-Materials in Medicine 13, 875–883 (2002).

Characterization

G. Caliskan, A. Kisliuk, A.M. Tsai, C.L. Soles, and

A.P. Sokolov, “Protein Dynamics in Viscous Solvents,”

Journal of Chemical Physics 118, 4230–4236 (2003).

S. Lin–Gibson, H.J. Walls, S.B. Kennedy, and

E.R. Welsh, “Reaction Kinetics and Gel Properties

of Blocked Diisocyanate Cross-Linked Chitosan

Hydrogels,” Carbohydrate Polymers, (in press).

F.W. Wang and R.E. Lowry, “Wavelength-shift

Fluorescence Probes for Cure Monitoring of Resins,”

in Society for Biomaterials 29th Annual Meeting

Transactions, 340, April 2003, Reno, NV.

Polymers Division FY03 Annual Report Publication List
50

M.A. Spalding, D.W. Baugh, K.A. Koppi,

W.C. Buzanowski, A.J. Bur, and S.C. Roth, “Temperature

Gradients in the Channels of a Single-Screw Extruder,”

in Proceedings of the Annual Technical Meeting of the

Society of Plastics Engineers, 202–206, May 2003,

Nashville, TN.

Nanoscale Manufacturing

P.M. McGuiggan and D.J. Yarusso, “Measuring

the Mechanical Properties of a Thin Polymeric Film

by AFM,” ACS Polymeric Materials: Science and

Engineering 88, 532 (2003).

J.A. Pathak and K.B. Migler, “Droplet-String

Deformation and Stability During Micro-Confined

Shear Flow,” Langmuir, (in press).

J.A. Pathak, E. Robertson, S.D. Hudson, and

K.B. Migler, “Droplet Microstructure and String

Stability in Sheared Emulsions: Role of Finite-Size

Effects,” in Nonlinear Dynamics in Polymeric Systems,

edited by J. Pojman and Q. Tran-Cong (Washington,

D.C.: American Chemical Society, 2003).

F.R. Phelan and N.S. Martys, “Simulation of

Droplet Breakup Using a Lattice Boltzmann Method,”

in Proceedings of the Annual Technical Meeting of the

Society of Plastics Engineers, 2340–2344, May 2003,

Nashville, TN.

Y. Son, N.S. Martys, J.G. Hagedorn, and

K.B. Migler, “Suppression of Capillary Instability of

a Polymeric Thread via Parallel Plate Confinement,”

Macromolecules 36, 5825–5833 (2003).

Y. Son and K.B. Migler, “Interfacial Tension

Measurement Between Immiscible Polymers:

Improved Deformed Drop Retraction Method,”

Polymer 43, 3001–3006 (2002).

H. Wang, M.P. Nieh, E.K. Hobbie, C.J. Glinka,

and J. Katsaras, “Kinetic Pathway of the Bilayer-Micelle

to Perforated-Lamellae Transition,” Physical Review E,

Rapid Communication 67, 060902(R) (2003).

Nanocomposite Processing

A.J. Bur and M. McBrearty, “A Dielectric Slit Die

for In-line Monitoring of Polymer Compounding,” in

Proceedings of the Annual Technical Meeting of the

Society of Plastics Engineers, 3321–3325, May 2003,

Nashville, TN.

A.J. Bur and S.C. Roth, “Fluorescence Temperature

Measurements: Methodology for Applications to

Processing,” Polymer Engineering and Science,

(in press).

Processing Characterization

Complex Polymer Flow and Instabilities

A.J. Bur, S.C. Roth, D.W. Baugh, K.A. Koppi,

M.A. Spalding, J. Gunderson, and W.C. Buzanowski,

“Measuring Resin Temperature During Extrusion Using

a Fluorescence Technique,” in Proceedings of the

Annual Technical Meeting of the Society of Plastics

Engineers, 3341–3345, May 2003, Nashville, TN.

S.D. Hudson, “Wall Migration and Shear-Induced

Diffusion of Fluid Droplets in Emulsions,” Physics of

Fluids 15, 1106–1113 (2003).

S.D. Hudson, A.M. Jamieson, and B. Burkhart,

“The Effect of Surfactant on the Efficiency of

Shear-Induced Drop Coalescence,” Journal of Colloid

and Interface Science, (in press).

S.B. Kharchenko, K.B. Migler, and P.M. McGuiggan,

“Flow Induced Coating of Polymer Processing

Additives: Development of Frustrated Total Internal

Reflection Imaging,” in Proceedings of the Annual

Technical Meeting of the Society of Plastics Engineers,

2689–2693, May 2003, Nashville, TN.

M.M. Malwitz, S. Lin–Gibson, E.K. Hobbie,

P.D. Butler, and G. Schmidt, “Orientation of Platelets

in Multilayered Nanocomposite Polymer Films,”

Journal of Polymer Science: Polymer Physics Edition

(in press).

K.B. Migler, Y. Son, F. Qiao, and K.M. Flynn,

“Extensional Deformation, Cohesive Failure, and

Boundary Conditions During Sharkskin Melt Fracture,”

Journal of Rheology 46, 383–400 (2002).

J.A. Pathak, M.C. Davis, S.D. Hudson, and

K.B. Migler, “Layered Droplet Microstructures in

Sheared Emulsions: Finite-Size Effects,” Journal of

Colloid and Interface Science 255, 391–402 (2002).

J.A. Pathak, S.D. Hudson, and K.B. Migler,

“Structure Formation in Micro-Confined Polymeric

Emulsions,” ACS Polymer Preprints 43, 833–834

(2002).

Y. Son and K.B. Migler, “Cavitation of Polyethylene

During Extrusion Processing Instabilities,” Journal

of Polymer Science: Part B Polymer Physics 40,

2791–2799 (2002).

Y. Son and K.B. Migler, “Observation of the

Cavitation Phenomena Upon the Gross Melt Fracture

Regime In LLDPE Extrusion,” in Proceedings of the

Society of Plastics Engineers 2002 Annual Technical

Conference, May 20, 2002, San Francisco, CA.

Polymers Division FY03 Annual Report Publication List
51

A.J. Bur, S.C. Roth, and M. McBrearty, “Monitoring

Polymer/Clay Nanocomposite Compounding Using

a Dielectric Slit Die,” in Proceedings of the Annual

Technical Meeting of the Society of Plastics Engineers,

3326–3330, May 2003, Nashville, TN.

C.H. Davis, L.J. Mathias, J.W. Gilman,

D.A. Schiraldi, J.R. Shields, P. Trulove, T.E. Sutto,

and H.C. Delong, “The Effects of Melt Processing

Conditions on the Quality of Poly(ethylene

terephthalate) Montmorillonite Clay Nanocomposites,”

Journal of Polymer Science, Part B, Polymer Physics

40, 2661–2666 (2002).

V. Ferreiro, G. Schmidt, C.C. Han, and A. Karim,

“Dispersion and Nucleating Effects of Clay Fillers

in Nanocomposite Polymer Films,” in Polymer

Nanocomposites: Synthesis, Characterization and

Modeling, edited by R. Krishnamoorti and R. Vaia

(Washington, D.C.: American Chemical Society,

2002) Chap. 14, pp. 177–191.

S.C. Glotzer and F.W. Starr, “Multiscale Modeling

of Filled and Nanofilled Polymers,” Proceedings of

Foundations of Molecular Modeling and Simulation,

(in press).

L. Granasy, T. Pusztai, J.A. Warren, J.F. Douglas,

T. Borzsonyi, and V. Ferreiro, “Growth of ‘Dizzy

Dendrites’ in a Random Field of Foreign Particles,”

Nature Materials 2, 92–96 (2003).

E.K. Hobbie, H. Wang, H. Kim, C.C. Han,

E.A. Grulke, and J. Obrzut, “Optical Measurements of

Structure and Orientation in Sheared Carbon-Nanotube

Suspensions,” Review of Scientific Instruments 74,

1244–1250 (2003).

E.K. Hobbie, H. Wang, H. Kim, S. Lin–Gibson,

and E.A. Grulke, “Orientation of Carbon Nanotubes

in a Sheared Polymer Melt,” Physics of Fluids 15,

1196–1202 (2003).

Y. Jiang, A. Saxena, T. Lookman, and J.F. Douglas,

“Influence of Filler Particles and Clusters on Phase

Separation in Binary Polymer Blends,” Journal of the

Materials Research Society, (in press).

T. Kashiwagi, E. Grulke, J. Hilding, R. Harris,

A. Awad, and J.F. Douglas, “Thermal Degradation and

Flammability Properties of Poly(propylene)/Carbon

Nanotube Composites,” Macromolecular Rapid

Communications 23, 761–765 (2002).

S. Lin–Gibson, G. Schmidt, J. Pathak, and

C.C. Han, “Rheology of Poly(ethylene oxide)/Clay

Solutions,” ACS Polymeric Materials: Science and

Engineering 87, 14–15 (2002).

S. Salaniwal, S.K. Kumar, and J.F. Douglas,

“Amorphous Solidification in Polymer-Platelet

Nanocomposites,” Phyical Review Letters 89,

art. no. 258301 (2002).

H. Wang and E.K. Hobbie, “Amphiphobic

Carbon Nanotubes as Macroemulsion Surfactants,”

Langmuir 19, 3091–3093 (2003).

Multivariant Measurement Methods

Combinatorial Methods Development

E.J. Amis, X.D. Xiang, and J.C. Zhao,

“Combinatorial Materials Science: What’s New

Since Edison?” MRS Bulletin 27, 295–300 (2002).

K.L. Beers, J.F. Douglas, E.J. Amis, and A. Karim,

“Combinatorial Measurements of Crystallization Growth

Rate and Morphology in Thin Films of Isotactic

Polystyrene,” Langmuir 19, 3935–3940 (2003).

M.Y.M. Chiang, R. Song, J. He, A. Karim, W.L. Wu,

and E.J. Amis, “Combinatorial Edge Delamination Test

for Thin Film Adhesion — Concept, Procedure and

Results,” in 3rd European Structural Integrity Society

Conference on Fracture of Polymers, Composites

and Adhesives, September 2003, Les Diablerets,

Switzerland, (in press).

M.Y.M. Chiang, R. Song, A. Karim, and E.J. Amis,

“Multivariant Measurement for Thin Film Adhesion as

a Function of Temperature and Thin Film Thickness,”

in Nano Tech 2003, February 2003, San Francisco, CA.

M.Y.M. Chiang, W.L. Wu, J. He, and E.J. Amis,

“Combinatorial Approach to the Edge Delamination

Test for Thin Film Reliability,” Thin Solid Films 437,

197–203 (2003).

A.J. Crosby, A. Karim, and E.J. Amis,

“Combinatorial Investigations of Interfacial Failure,”

Journal of Polymer Science Part B — Polymer Physics

41, 883–891 (2003).

C.H. Davis, K.L. Beers, A.M. Forster,

C.M. Stafford, A.P. Smith, C. Harrison, W. Zhang,

A. Karim, and E.J. Amis, “Polymer Science at the

NIST Combinatorial Methods Center,” ACS Polymeric

Materials: Science and Engineering 88, 386–387

(2003).

A.M. Forster, C. Stafford, A. Karim, and E.J. Amis,

“Combinatorial Adhesion Measurement: Data Collection

and Library Evaluation,” ACS Polymeric Materials:

Science and Engineering 88, 490–491 (2003).

Polymers Division FY03 Annual Report Publication List
52

C. Harrison, J.A. Dagata, and D.H. Adamson,

“Lithography with Self-Assembled Copolymer

Microdomains,” in Developments in Block Copolymer

Science and Technology, (in press).

J.D. Hewes, D. Kaiser, A. Karim, and E.J. Amis,

“Combinatorial Methods for Materials Research and

Development — Contribution to Section on “Polymeric

Materials,” in Encyclopedia of Chemical Technology,

(Kirk–Othmer Online, Wiley Interscience), (in press).

A. Karim, A. Sehgal, J.C. Meredith, A.J. Crosby,

and E.J. Amis, “Image Analysis for High-Throughput

Materials Science,” in High Throughput Analysis —

A Tool for Combinatorial Materials Science,

edited by R.A. Potyrailo and E.J. Amis (New York:

Kluwer Academic/Plenum Publishers), Chap. 3, (in press).

J.C. Meredith, A.P. Smith, A.J. Crosby, E.J. Amis,

and A. Karim, “Combinatorial Methods for Polymer

Science,” in Encyclopedia of Polymer Science and

Technology, (New York: John Wiley & Sons, Inc.,

2002).

J.C. Meredith, A.P. Smith, A. Karim, and E.J. Amis,

“Combinatorial Polymer Science: Synthesis and

Characterization,” in ACS Symposium Series, edited by

Ripudaman Malhotra (Washington, D.C.: American

Chemical Society, 2002) Chap. 2.

S.V. Roberson, A. Sehgal, A. Fahey, and A. Karim,

“Time-Of-Flight Secondary Ion Mass Spectrometry

(Tof-SIMS) For High-Throughput Characterization

Of Biosurfaces,” Applied Surface Science 203–204,

855–858 (2003).

C.M. Stafford, A.M. Forster, C.K. Harrison,

C.H. Davis, E.J. Amis, and A. Karim, “High-Throughput

Measurements of Polymer Adhesion and Mechanical

Properties,” in ACS Polymeric Materials: Science and

Engineering, September 2003, New York, (in press).

C.M. Stafford, C. Harrison, A. Karim, and

E.J. Amis, “Measuring Modulus of Gradient Polymer

Films by Strain-Induced Bucking Instabilities,”

ACS Polymer Preprints 43, 1335 (2002).

Surface and Polymer Interactions

K.M. Ashley, J.C. Meredith, E. Amis, D. Raghavan,

and A. Karim, “Combinatorial Investigation of

Dewetting: Polystyrene Thin Films on Gradient

Hydrophilic Surfaces,” Polymer 44, 769–772 (2003).

K.M. Ashley, A. Sehgal, E.J. Amis, D. Raghavan,

and A. Karim, “Combinatorial Mapping of Polymer

Film Wettability on Gradient Energy Surfaces,”

Materials Research Society Symposium Proceedings on

Organic/Biological Materials and Devices: Polymeric

Interfaces and Thin Films 700, S4.7.1–6 (2002).

J.T. Elliot, D.L. Burden, J.T. Woodward, A. Sehgal,

and J.F. Douglas, “Phospholipid Monolayers Supported

on Spun Cast Polystyrene Films,” Langmuir 19,

2275–2283 (2003).

M.J. Fasolka, L.S. Goldner, J. Hwang, A.M. Urbas,

P. DeRege, T. Swager, and E.L. Thomas, “Measuring

Local Optical Properties: Near-Field Polarimetry of

Photonic Block Copolymer Morphology,” Physical

Review Letters 90, 016107–1:4 (2003).

A.M. Forster and S.M. Kilbey, “The Influence of

Shearing Parameters on the Friction Force Measured

Between Polymer Brushes,” ACS Polymer Preprints 44,

502–503 (2003).

S.N. Goldie, M.J. Fasolka, L.S. Goldner, J. Hwang,

and K.L. Beers, “Near-Field Polarimetric Characterization

of Semi-Crystalline Polymer Systems,” ACS Polymeric

Materials: Science and Engineering 88, 145–146 (2003).

L.S. Goldner, M.J. Fasolka, S. Nougier,

H.P. Nguyen, G.W. Bryant, J. Hwang, K.D. Weston,

K.L. Beers, A. Urbas, and E.A. Thomas, “Fourier

Analysis Near-Field Polarimetry for Measurement

of Local Optical Properties of Thin Films,” Applied

Optics 42, 3864–3881 (2003).

X. Gu, D. Raghavan, J.F. Douglas, and A. Karim,

“Hole Growth Instability in the Dewetting of

Evaporating Polymer Solution Films,” Journal of

Polymer Science, Part B — Polymer Physics 40,

2825–2832 (2002).

X. Gu, M.R. VanLandingham, M. Fasolka,

J.W. Martin, J.Y. Jean, and T. Nguyen, “Enhancing

Sensitivity of Atomic Force Microscopy for

Characterizing Surface Chemical Heterogeneity,”

in Proceedings of the 26th Annual Meeting of the

Adhesion Society, Inc., “Adhesion Fundamentals:

From Molecules to Mechanisms and Modeling,”

185–187, February 2003, Myrtle Beach, SC.

J.C. Meredith, J.L. Sormana, B.G. Keselowsky,

A.J. Garcia, A. Tona, A. Karim, and E.J. Amis,

“Combinatorial Characterization of Cell Interactions

with Polymer Surfaces,” Journal of Biomedical

Materials Research, (in press).

A. Sehgal, V. Ferreiro, J.F. Douglas, E.J. Amis, and

A. Karim, “Pattern-Directed Dewetting of Ultrathin

Polymer Films,” Langmuir 18, 7041–7048 (2002).

A.P. Smith, A. Sehgal, J.F. Douglas, A. Karim, and

E.J. Amis, “Combinatorial Mapping of Surface Energy

Effects on Diblock Copolymer Thin Film Ordering,”

Macromolecular Rapid Communications 24, 131–135

(2003).

Polymers Division FY03 Annual Report Publication List
53

Polymers Division

Polymers Division

Chief

Eric J. Amis

Phone: 301–975–6762

E-mail: eric.amis@nist.gov

Deputy Chief

Chad R. Snyder

Phone: 301–975–4526

E-mail: chad.snyder@nist.gov

Senior Scientist

Wen-li Wu

Phone: 301–975–6839

E-mail: wen-li.wu@nist.gov

Group Leaders

Characterization and Measurement —

Method Development/Internal Capabilities

Chad R. Snyder

Standards and Data

Bruno M. Fanconi

Phone: 301–975–6769

E-mail: bruno.fanconi@nist.gov

Electronics Materials

Eric K. Lin

Phone: 301–975–6743

E-mail: eric.lin@nist.gov

Biomaterials

Newell R. Washburn

Phone: 301–975–4348

E-mail: newell.washburn@nist.gov

Processing Characterization

Kalman Migler

Phone: 301–975–4876

E-mail: kalman.migler@nist.gov

Multivariant Measurement Methods

Alamgir Karim

Phone: 301–975–6588

E-mail: alamgir.karim@nist.gov
54

Research Staff

Research Staff

Amis, Eric J.

eric.amis@nist.gov

Neutron, x-ray and light scattering

Polyelectrolytes

Viscoelastic behavior of polymers

Dendrimers and dendritic polymers

Functional biomaterials

Anopchenko, Oleksiy S.+

oleksiy.anopchenko@nist.gov

Dielectric relaxation spectroscopy

X-ray scattering

Microwave spectroscopy techniques

Antonucci, Joseph M.

joseph.antonucci@nist.gov

Synthetic and polymer chemistry

Dental composites, cements and adhesion

Initiator systems

Interfacial coupling agents

Remineralizing polymer systems

Arnould, Mark

mark.arnould@nist.gov

Mass spectrometry

Free-radical polymerization

Ashley, Karen+

karenmashley@hotmail.com

Polymer thin films

Dewetting

Combinatorial measurements

Balizer, Edward+

Neutron, x-ray scattering

Polymer electrostriction

Bailey, LeeAnn O.

+

leeann.bailey@nist.gov

Cell biology

Apoptosis

Inflammatory responses

Flow cytometry

Polymerase chain reaction

Bauer, Barry J.

barry.bauer@nist.gov

Polymer synthesis thermal characterization

Neutron, x-ray and light scattering

Dendrimers, metallic ions nanocluster

Porous low-k thin film characterization

Becker, Matt

matt.becker@nist.gov

Polymer synthesis

Block copolymers

Peptide synthesis

Phage display

Combinatorial methods

Beers, Kathryn

kathryn.beers@nist.gov

Crystallization in thin films

Optical light scattering

Controlled/living polymerizations

Polymer formulations

Polymer synthesis

Bencherif, Sidi+

sidi.bencherif@nist.gov

Mass spectrometry

Chemical modification

Blair, William R.

william.blair@nist.gov

Polymer analysis by size exclusion

chromatography

Mass spectrometry of polymers

High temperature viscometry

Rayleigh light scattering

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

Byrd, H. Michelle

michelle.byrd@nist.gov

Mass spectrometry of polymers

Nuclear Magnetic Resonance

Cabral, Joao+

joao.cabral@nist.gov

Polymeric rapid prototyping

Polymer phase separation

Millifluidic measurements
55

Research Staff

Carey, Clifton M.*

clifton.carey@nist.gov

Dental plaque

Microanalytical analysis techniques

Fluoride efficacy for dental health

De and remineralization

Phosphate chemistry

Ion-selective electrodes

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

Chiche, Arnaud+

arnaud.chiche@nist.gov

Adhesion on rough surfaces

Cavitation in peel test

Polymer adhesion

Chow, Laurence C.*

laurence.chow@nist.gov

Calcium phosphate compounds and biomaterials

Dental and biomedical cements

Solution chemistry

Topical dental fluorides

Cicerone, Marcus T.

marcus.cicerone@nist.gov

Protein stabilization

Glass transition theory

Optical coherence microscopy

Tissue engineering scaffolds

Confocal microscopy

Cooper, James A.

james.cooper@nist.gov

Tissue engineering

Polymer scaffolds

Cell biology

Optical microscopy

Cygan, Zuzanna+

zcygan@umich.edu

Polymer formulations

Florescent probe studies

Millifluidics of polymer solutions

Combinatorial and high-throughput methods

Davis, Cher

cher.davis@nist.gov

NIST Combinatorial Methods Center

Polymer nanocomposites

Polymers synthesis

Combinatorial methods and measurements

DeReggi, Aime S

aime.dereggi@nist.gov

Polarization-depth profiles in polymers

Space charge in dielectrics

Ferroelectric polymers

Polymeric piezo- & pyroelectric devices

Biodegradation of polymers

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 polymers at interfaces

Scaling and renormalization group calculation

Conductivity/viscosity of nanoparticle

filled systems

Crystallization of polymers

Duan, Hu+

hu.duan@nist.gov

Electron microscopy

Self-assembly and liquid crystals

Dunkers, Joy P.

joy.dunkers@nist.gov

Optical coherence microscopy

Image analysis

Fiber optic spectroscopy

Infrared microspectroscopy of polymers

Confocal fluorescence microscopy

Eichmiller, Frederick C.*

frederick.eichmiller@nist.gov

Clinical dentistry

Composites

Dentin adhesives
56

Eidelman, Naomi N.*

naomi.eidelman@nist.gov

Infrared mapping for surface chemistry

Characterization of calcified deposits by FTIR

Infrared microscopy

Fanconi, Bruno M.

bruno.fanconi@nist.gov

Infrared & Raman spectroscopy of polymers

Structure of polymers

Polymer fracture

Process monitoring of polymer composites

Fasolka, Michael J.

mfasolka@nist.gov

Combinatorial methods and measurements

Nanopatterned substrates

Nanohybrid structures

Surface energy patterning and control

Surfaces and interfaces

Informatics standards

Scanning probe microscopy

Flaim, Glenn M.*

glenn.flaim@nist.gov

Fabricating dental composites

Floyd, Cynthia J. E.*

cynthia.floyd@nist.gov

Dental composites

Nuclear magnetic resonance

Flynn, Kathleen M.

kathleen.flynn@nist.gov

Melt flow rate measurements

Size exclusion chromatography

Mass spectrometry of polymers

Forster, Aaron M.

aaron.forster@nist.gov

Combinatorial methods and measurements

Polymer adhesion

Polymer interfaces

Biopolymer interactions

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

Network Administrator

Giuseppetti, Anthony A.*

anthony.giuseppetti@nist.gov

Casting of dental alloys

Scanning electron microcopy

Dental materials testing

Guttman, Charles M.

charles.guttman@nist.gov

Solution properties of polymers

Size exclusion chromatography

Mass spectrometry of 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

Harrison, Christopher

christopher.harrison@nist.gov

Combinatorial methods

Mechanical properties

Polymer thin film properties

Modulus measurements

Hedden, Ronald C.

ronald.hedden@nist.gov

Siloxane polymers: synthesis and properties

Nanoporous thin films

Gel permeation chromatography

Dendrimers

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:

Polymer chemistry

Mass spectroscopy

Nanocomposites

Research Staff
57

Hudson, Steven D.

steven.hudson@nist.gov

Electron microscopy

Polymeric surfactant and interfacial dynamics

Self-assembly and liquid crystals

Nanocomposites

Biomaterials

Hu, Tengjiao+

tengjiao.hu@nist.gov

Neutron, x-ray, and light scattering

Conformation of polymer chains in solution and

at interfaces

Imperfections in crystals

Hussain, Latiff*

latiff.hussain@nist.gov

Monomer polymer synthesis, characterization,

testing

Dental composites, adhesives

Jablonski, Erin L.

erin.jablonski@nist.gov

Near-edge x-ray absorption fine structure

spectroscopy

Polymer diffusion, surfaces, thin films

Polymer phase behavior

Jones, Ronald L.

ronald.jones@nist.gov

Neutron and x-ray scattering

Neutron reflectivity

Polymer surfaces and thin films

Polymer phase transitions and computer simulation

Julthongpiput, Duangrut+

duangrut@hotmail.com

Combinatorial methods and measurements

Polymer adhesion and mechanical properties

Scanning probe microscopy

Kano, Kenj+

kkano@nist.gov

Dielectric relaxation of polymers

Nonlinear dielectric and conductive spectroscopy

Kapeeleshwar, Krishna+

kapeeleshwar.Krishana@us.rhodia.com

Polymer mixing strategies

Polymer coatings

Polymer formulations

Karim, Alamgir

alamgir.karim@nist.gov

Combinatorial and high-throughput methods

Combinatorial measurements

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

Nanofilled polymer films

Kee, Tak+

tak.kee@nist.gov

Ultrafast spectroscopy

CARS microscopy

Tissue engineering scaffolds

Confocal microscopy

Kennedy, Scott B.

scott.kennedy@nist.gov

Tissue engineering

Biomaterials

Block copolymers

Combinatorial surface patterns

Kharchenko, Semen+

semen.kharchenko@nist.gov

Stress optical properties

Birefringence

Viscoelastic properties

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, Jae Hyun+

jaehyun@nist.gov

Fiber/matrix interface

Mechanical properties

Polymer composites

Landis, Forrest A.

forrest.landis@nist.gov

Crystallization and melting of miscible polymer

blends

Ionomers

Optical coherence microscopy

Tissue engineered scaffolds

Static small angle laser light scattering

Research Staff
58

Lee, Hae-Jeong+

hae-jeong.lee@nist.gov

X-ray reflectivity

Small-angle neutron scattering

Structural characterization of low dielectric

constant thin films

Porosimetry of porous thin films/light-emitting

diode (LED)

Lee, Yu-Hsin (Mandy)+

yu-hsin.lee@nist.gov

Dielectric relaxation spectroscopy

Nanocomposites

Atomic force microscopy

Rubber-toughened phenolic resins

Dynamic mechanical analysis of polymer blends

Lenhart, Joseph L.+

jllenha@sandia.gov

Sensors

Interphase structure

Polymer films and interfaces

Near-edge x-ray absorption fine structure

X-ray and neutron reflectivity

Liao, Nam S.*

nam.liao@nist.gov

Synthesis and testing of dental adhesives

Internal stress of composition due to

polymerization

Web page development

Lin, Eric K.

eric.lin@nist.gov

Polymer thin films and interfaces

Polymeric photoresists for lithography

Small angle neutron scattering

Statistical mechanics

X-ray and neutron reflectivity

Lin-Gibson, Sheng

sheng.lin-gibson@nist.gov

Rheology of gels & nanocomposites

Mass spectrometry of synthetic polymers

Polymer synthesis and modification

Structure and dynamics of nanocomposite

polymeric materials

Liu, D.-W.

da-wei.liu@nist.gov

Polymer synthesis

Thermal gravimetric analysis

Differential scanning calorimetry

Gel permeation chromatography

Infrared spectroscopy

Nuclear magnetic resonance

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

Maurey, John R.+

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

Dental materials

McGuiggan, Patricia

patricia.mcguiggan@nist.gov

Atomic force microscopy

Viscoelastic properties

Mei, Ying+

ying.mei@nist.gov

Polymer synthesis

Peptide synthesis

Biodegradable polymers

Biomimetic polymers

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

Noda, Natsuko+

natsuko.noda@nist.gov

Impedence spectroscopy

Dielectric characterization of composites

Photolithography

Nanocomposites

Research Staff
59

Norman, Alexander+

alexander.norman@nist.gov

Polymer formulations

Water soluble polymers

Microemulsions

Neutron and x-ray scattering from polymers

Obrzut, Jan

jan.obrzut@nist.gov

Dielectric relaxation spectroscopy

Electronic properties of polymers and composites

Electronic packaging

Microwave and optical waveguides

Photoelectron spectroscopy (x-ray and UV)

Reliability, stress testing

Parry, Edward E.*

edward.parry@nist.gov

Dental appliance and crown and bridges

fabrication

Machine shop applications

Pathak, Jai A.+

jai.pathak@nist.gov

Polymer rheology

Polymer dynamics

Glass transition

Polymer blends

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

Prabhu, Vivek M.

vmprabhu@nist.gov

Small-angle neutron scattering

Polyelectrolytes

Light scattering

Fluorescence correlation spectroscopy

Polymer thin films

X-ray and neutron reflectivity

Quinn, Janet*

janet.quinn@nist.gov

Fractography

Composites

Raghavan, Dharmaraj+

draghavan@howard.edu

Curing of epoxies

High-throughput and combinatorial measurements

Confocal microscopy

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

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

Shimizu, Katsumi+

Polymer blends

Polymer crystallization and melting

Phase contrast optical microscopy

Silverstein, Michael S.+

michael.silverstein@nist.gov

Porous low-k dielectrics

Small angle neutron scattering

X-ray reflectivity

Plasma polymerization

Polymer films for electronic applications

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

Amorphous calcium phosphates as dental

materials

Research Staff
60

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

Nanocomposite properties

Soles, Christopher L.

csoles@nist.gov

Polymer dynamics

Inelastic neutron scattering

Low-k dielectric thin films

X-ray and neutron reflectivity techniques

Polymer thin films and lithography

Ion beam scattering techniques

Song, Rui+

rsong@nist.gov

Combinatorial methods and measurements

Polymer debonding

Polymer adhesion and failure

Polymeric peel tests

Stafford, Christopher

chris.stafford@nist.gov

Polymer adhesion

Surfaces and interfaces

Polymer thin films

Starr, Francis

francis.starr@nist.gov

Dynamics of filled polymers

Slow dynamics in soft condensed matter

Molecular dynamics simulations and parallel

Computational methods

Start, Paul R.+

paul.start@nist.gov

nanocomposites

TEM

Sol-gel processes

Surfactants and interfacial tension

Takagi, Shozo*

shozo.takagi@nist.gov

Crystallography

X-ray diffraction

Calcium phosphate biomaterials

Topical fluoridation

De- and remineralization

Tesk, John A.

john.tesk@nist.gov

Biomaterials: industrial relations

Characterization: biomaterials; physical and

mechanical properties

Reference biomaterials

Reference data for biomaterials

Biomaterials: orthopaedics, cardiovascular,

dental, opthalmic, & tissue engineered

medical devices

Standards for medical devices

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 Workum, Kevin

kevin.vanworkum@nist.gov

Monte Carlo and molecular dynamics simulations

Mechanical properties of glassy and crystalline

structures

Dispersion in nanocomposites

Vogel, Gerald L.*

gerald.vogel@nist.gov

Dental plaque chemistry, chemistry of calcium

phosphates

Microanalytical techniques

Vogt, Bryan D.

bryan.vogt@nist.gov

Polymer thin film properties

X-ray and neutron reflectivity

Interfacial effects

Ordered mesoporous materials

Wallace, William E.

william.wallace@nist.gov

Mass spectrometry

Geometric data analysis methods

Walls, Howard J.

howard.walls@nist.gov

Rheology of polymers

Combinatorial measurements and methods

Viscoelastic polymers

Research Staff
61

Wang, Chia-Ying+

cywang@nist.gov

Small-angle x-ray scattering

Polymer diffusion

Microphase transitions of block copolymers

Fluorescence spectroscopy of polymers

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

Wang, Michael X.+

mwang@nist.gov

Small angle x-ray & neutron scattering

X-ray & neutron reflectivity

Light scattering

Polymer thin films

Combinatorial methods

Wang, Xianfeng+

xianfeng.wang@nist.gov

Monte Carlo simulations

Finite element modeling

Polymer composites

Mechanical properties

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

Wetzel, Stephanie J.

stephanie.wetzel@nist.gov

Mass spectrometry of polymers

Chemometrics

Size exclusion chromatography

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

Wu, Tao+

tao.wu@nist.gov

Polymer formulations

Polymer synthesis

Interfacial tension measurements

Combinatorial and high-throughput methods

Yurekli, Koray+

kyurekli@Jetson.uh.edu

Polymer nanocomposite

Phase separation

Thin films and interfaces

Neutron and light scattering

Xu, Huakun*

hockin.xu@nist.gov

Remineralizing composites

Wear and fatigue

Fiber and whisker reinforcement

Zhang, Kai+

kai.zhang@nist.gov

Polymer scaffolds

Tissue engineering

Dental resins

Combinatorial methods

Zhang, Wenhua+

wezhang@nist.gov

Combinatorial and high-throughput informatics

Database structure

Laboratory automation

Polymer thin films and blends

* Research Associate

+ Guest Scientist

Research Staff
62
63

Organizational Charts

Organizational Charts

Materials Science and Engineering Laboratory

Polymers

E.J. Amis, Chief

C.R. Snyder, Deputy

Metallurgy

C.A. Handwerker, Chief

F.W. Gayle, Deputy

Ceramics

D.L. Kaiser, Chief

D.R. Black, Deputy

Materials Reliability

A.F. Clark, Chief

T.A. Siewert, Deputy

NIST Center for

Neutron Research

J.M. Rowe, Director

Director

Deputy Director

National Institute of Standards and Technology

Director

Boulder Laboratories

Baldrige National Quality

Program

Director for

Administration

& Chief Financial

Officer

Technology

Services

Advanced

Technology

Program

Manufacturing

Extension

Partnership

Manufacturing

Engineering

Laboratory

Chemical Science

and Technology

Laboratory

Materials Science

and Engineering

Laboratory

Electronics and

Electrical Engineering

Laboratory

Information

Technology

Laboratory

Physics

Laboratory

Building and

Fire Research

Laboratory

L.E. Smith, Director

S.W. Freiman, Deputy Director
64

Eric J. Amis, Chief

Chad R. Snyder, Deputy Chief

Wen-li Wu, Senior Scientist

Dawn Bradley, Division Secretary

Diane Fernandez, Administrative Officer

Lisa Fedders, Administrative Assistant

Linda Souders, Secretary

Polymers Division (854.00)

Characterization and Measurement

(854.01)

Chad R. Snyder, Leader

Bronny Webb, Secretary

Organizational Charts

A. Bur

D. Fry

E. Hobbie

S. Hudson

S. Lin–Gibson

P. McGuiggan

F. Phelan

S. Roth

H. Duan

S. Kharchenko

G. Matsuba

M. Meillon

D. Morgan

J. Pathak

P. Start

K. Beers

C. Davis

M. Fasolka

A. Forster

C. Stafford

H. Walls

K. Ashley

J. Cabral

A. Chiche

Z. Cygan

K. Kapeeleshwar

A. Norman

M. Wang

W. Zhang

Processing

Characterization (854.05)

Kalman Migler, Leader

Lisa Long, Secretary

Multivariant Measurement

Methods (854.06)

Alamgir Karim, Leader

Lisa Long, Secretary

J. Antonucci

M. Becker

J. Cooper

S. Kennedy

K. O’Brien

C. Simon

F. Wang

M. Weir

K. Wilson

L. Bailey

S. Bencherif

C. Khatri

Y. Mei

N. Richards

E. Schwartz

A. Sehgal

K. Zhang

Biomaterials

(854.03)

Newell Washburn, Leader

Lisa Long, Secretary

O. Anopchenko

D. Ho

T. Hu

K. Kano

H. Lee

S. Sambasivan

B. Bauer

C. Chiang

E. Jablonski

R. Jones

J. Obrzut

V. Prabhu

C. Soles

B. Vogt

M. Arnould

W. Blair

M. Byrd

K. Flynn

C. Guttman

J. Tesk

W. Wallace

S. Wetzel

Electronics Materials

(854.02)

Eric Lin, Leader

Bronny Webb, Secretary

Standards and Data

Bruno Fanconi, Leader

M. Chiang

M. Cicerone

A. DeReggi

J. Douglas

J. Dunkers

R. Hedden

G. Holmes

F. Khoury

F. Landis

D. Liu

W. McDonough

F. Starr

K. Van Workum

D. VanderHart

Method Development/

Internal Capabilities

Chad R. Snyder, Leader

S.A. Audino

J. Maurey

T. Kee

J. Kim

S. Liao

X. Wang