i

National Institute of

Standards and Technology

William Jeffrey

Director

Technology

Administration

Robert Cresanti

Under Secretary of

Commerce for Technology

U.S. Department

of Commerce

Carlos M. Gutierrez

Secretary Materials Science and

Engineering Laboratory

FY 2005 Programs and

Accomplishments

Polymers

Division

Eric J. Amis, Chief

Chad R. Snyder, Deputy Chief

NISTIR 7299

March 2006
ii

Certain commercial entities, equipment, or materials may be identified in this document in order to

describe an experimental procedure or concept adequately. Such identification is not intended to imply

recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended

to imply that the entities, materials, or equipment are necessarily the best available for the purpose.
iii

Table of Contents

Table of Contents

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

Technical Highlights

Direct Correlation of Organic Semiconductor Film Structure

to Field-Effect Mobility .......................................................................................................2

Chaotic Flow to Enable Soft Nanomanufacturing ..............................................................4

X-ray Reflectivity as a Tool for Characterizing Pattern Shape

and Residual Layer Thickness for Nanoimprint Lithography .............................................6

Gradient Libraries of Surface-Grafted Polymers:

Combi Tools for Surface Functionality ...............................................................................8

Quantifying Cellular Response to Biomaterials with

Macromolecular Assembly ...............................................................................................10

Nanometrology ........................................................................................................................13

Reference Specimens for SPM Nanometrology ..............................................................14

Nanotube Processing and Characterization ......................................................................15

Combinatorial Adhesion and Mechanical Properties ........................................................ 16

Soft Nanomanufacturing ...................................................................................................17

Defects in Polymer Nanostructures..................................................................................18

Critical Dimension Small Angle X-Ray Scattering ...........................................................19

Nanoimprint Lithography ..................................................................................................20

Materials for Electronics .........................................................................................................21

Polymer Photoresists for Nanolithography .......................................................................22

Organic Electronics...........................................................................................................23

Nanoporous Low-k Dielectric Constant Thin Films .........................................................24

Advanced Manufacturing Processes ......................................................................................25

NIST Combinatorial Methods Center

Pioneer and Partner in Accelerated Materials Research ........................................... 27

Polymer Formulations:

Materials Processing and Characterization on a Chip ...................................................... 28

Quantitative Polymer Mass Spectrometry ........................................................................29
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Table of Contents

Biomaterials .............................................................................................................................31

Combinatorial Methods for Rapid Characterization

of Cell-Surface Interactions..............................................................................................32

Cell Response to Tissue Scaffold Morphology .................................................................33

3-Dimensional In Situ Imaging for Tissue Engineering:

Exploring Cell/Scaffold Interaction in Real Time .............................................................34

Broadband CARS Microscopy for Cellular/Tissue Imaging ............................................ 35

Molecular Design and Combinatorial Characterization

of Polymeric Dental Materials .......................................................................................... 36

Safety and Reliability ...............................................................................................................37

Polymer Reliability and Threat Mitigation.........................................................................38

Polymers Division FY05 Annual Report Publication List ........................................................ 39

Polymers Division .................................................................................................................... 47

Research Staff.........................................................................................................................48

Organizational Charts ..............................................................................................................57
1

Executive Summary

I am pleased to report to you the results of a

strong year for the Polymers Division. Our staff and

researcher collaborators continue to be acknowledged

for their work in important areas, and in my summary,

I would like to note some of these recognitions received

this year.

As an agency of the Department of Commerce, the

National Institute of Standards and Technology (NIST)

focuses on work, often in collaboration with industry,

to foster innovation, trade, security, and jobs. This

year, our efforts have been recognized by two awards

specifically related to service to industry. Based on

research, patenting, and technology transfer activities

that resulted in commercialization of polymeric

amorphous calcium phosphate compositions as dental

restoratives, the Federal Laboratory Consortium (FLC)

awarded Joseph Antonucci the 2005 FLC Award for

Excellence in Technology Transfer. This prestigious

award, judged by representatives from industry,

state and local government, academia, and federal

laboratories, recognizes outstanding work in

transferring federal laboratory developed technology

to industry. Also this year, the Secretary of Commerce

awarded the Department of Commerce Silver Medal

for Customer Service to the NIST Combinatorial

Methods Center, specifically Eric J. Amis,

Kathryn L. Beers, Michael J. Fasolka, Alamgir

Karim, and Christopher M. Stafford, for excellence

in transferring NIST-developed combinatorial and

high-throughput measurement technologies to industry.

Silver Medals are awarded to those individuals or

groups that demonstrate exceptional performance

characterized by noteworthy or superlative

contributions that have a direct and lasting impact

within the Department of Commerce.

Complementing these awards for service to industry,

several scientists and engineers were acknowledged for

their outstanding scientific careers. In a White House

ceremony on June 13, 2005, Michael J. Fasolka was

awarded the Presidential Early Career Award for

Scientists and Engineers (PECASE), the nation’s

highest honor for professionals at the outset of their

independent research careers. Mike was recognized for

his experimental and theoretical studies of nanostructured

polymer films and for investigations extending the

power of next-generation scanned probe microscopy

techniques on structures designed to provide quantitative

measures of chemical, mechanical, and optoelectronic

nanoscale material properties. At the 2005 Annual

March meeting of the American Physical Society

(APS), Alamgir Karim was named a Fellow of Society

for his pioneering research on polymer thin films

and interfaces, polymer brushes, blend film phase

separation, thin film dewetting, pattern formation

in block copolymer films, and the application of

combinatorial measurement methods to complex

polymer physics. Acknowledging the breadth and

impact of his extremely productive career, NIST

named Wen-li Wu a Fellow of the Institute. Wen-li was

specifically recognized for the impact of his advances in

measurement methods to assist industry, developments

in the fundamentals of scattering, and significant

scientific insights in polymer physics.

Executive Summary

Sampling of journal and book covers featuring research

from the Polymers Division

This annual report provides a sample of the

outstanding research from the scientists and engineers

of the Polymers Division. I hope you enjoy reading

our highlights in areas ranging from nanomanufacturing

and nanofabrication to organic electronics and

combinatorial methods. As usual, only a portion

of our work is included in this report, so please

visit www.nist.gov/polymers for more details.

On our site, you can also download copies of any

of our publications.

As always, I welcome your comments.

Eric J. Amis

Chief, Polymers Division
2

Technical Highlights

Direct Correlation of Organic Semiconductor Film Structure

to Field-Effect Mobility

Organic electronics has dramatically emerged

in recent years as an increasingly important

technology encompassing a wide array of devices

and applications including embedded passive

devices, flexible displays, and sensors. Device

performance, stability, and function critically depend

upon charge transport and material interaction at the

interfaces of disparate materials. Near-edge x-ray

absorption fine structure (NEXAFS) spectroscopy

is demonstrated as a powerful tool to quantify

molecular orientation, degree of conversion, and

surface coverage of solution-processed organic

electronics materials as a function of processing

variables and materials characteristics.

Dean M. DeLongchamp and Eric K. Lin

Organic electronic devices are projected to

revolutionize new types of integrated circuits

through new applications that take advantage of

low-cost, high-volume manufacturing, nontraditional

substrates, and designed functionality. Progress in

organic electronics is slowed by concurrent development

of multiple material platforms and processes and a lack

of measurement standardization between laboratories.

A critical need exists for diagnostic probes, tools, and

methods to address these technological challenges.

Recent efforts towards large-scale adoption of

organic electronics have focused on maximizing device

performance using new molecular designs and processing

strategies. In particular, tremendous effort has been

directed towards solution-based processing strategies

where fabrication under ambient conditions is possible.

Significant progress has been made towards formulations

for ink-jet printing, spin-coating, or dip-coating. However,

rational design and systematic progress are hindered by

insufficient correlations between organic semiconductor

film structure and field-effect mobility in transistors.

Establishing direct correlations between the material

structure and device performance has been challenging.

These challenges are exemplified in recently developed

soluble precursor molecules shown in Figure 1 that

thermally convert into high-performance organic

semiconductors. Conversion of precursor films

involves changes in structure at many levels. First, the

chemical structure changes as solubilizing groups are

removed. Simultaneously, the molecules reorient with

respect to the substrate. Finally, large-scale molecular

reorganization causes the film to become thinner,

eventually reaching monolayer and sub-monolayer

coverage. Each of these changes strongly impacts the

performance of the semiconductor as an active layer in

organic field effect transistors (OFETs).

Figure 1: (Left) The conversion chemistry of an organic

semiconductor oligomer from an organic solvent soluble species

to an insoluble organic semiconductor. (Right) NEXAFS spectra

illustrating quantification of the degree of conversion as a

function of temperature.

To address these challenges, we developed and

applied near-edge x-ray absorption fine structure

(NEXAFS) spectroscopy to quantify the degree of

conversion, molecular orientation, and surface coverage of

organic semiconductor thin films. NEXAFS spectroscopy

was performed at the NIST/Dow soft x-ray materials

characterization facility at the National Synchrotron

Light Source (NSLS) of Brookhaven National Laboratory

(contact: Daniel Fischer, NIST Ceramics Division).

Carbon K-edge spectra were collected in partial electron

yield (PEY) mode with a sampling depth of ≈ 6 nm.

As cast, films of Pre-T6 in Figure 1 are approximately

20 nm thick. We expect the conversion, orientation, and

defects within the sampling volume to closely match

those of the mobile channel adjacent to the dielectric

layer of field effect transistor devices.

Figure 1 shows the conversion chemistry of an

oligothiophene that is initially soluble in organic

solvents but undergoes thermolysis at elevated

temperatures to become an organic semiconductor that

is insoluble in organic solvents. The carbon K-edge

spectra in Figure 1 exhibit peaks that quantify the

degree of conversion. From these spectra, degrees of

conversion between the precursor and product can be

obtained over the full practical range of annealing

temperatures. The NEXAFS spectra provide clear

signatures of the conversion chemistry even in very

thin films.
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Figure 3: NEXAFS measurements of the orientation of the

molecules as a function of temperature. The molecular

orientation changes as the material undergoes chemical

conversion. Figure 2: The geometry of near-edge x-ray absorption fine

structure (NEXAFS) spectroscopy for the determination of the

orientation of an oligothiophene organic semiconductor.

NEXAFS spectroscopy can also be used to measure

the molecular orientation of oligothiophene molecules

because the incident synchrotron soft x-rays are

polarized. The carbon–carbon π* and σ* resonant

intensities (Figure 2) exhibit a strong angular incidence

dependence that corresponds to an oriented resonance

defined by the spatial orientation of the final state

orbital. The π* intensity is largest at normal incidence

(90 °), indicating that the conjugated plane of the

product tilts away from the substrate in an “edge-on”

orientation. The σ* intensity is greatest at glancing

incidence (20 °), indicating that the long axis is normal

to the substrate in a “standing up” orientation.

The changes in molecular orientation accompanying

thermolysis are quantified using a dichroic ratio, R,

defined in Figure 2. R varies between +0.75 and –1.00,

where a more positive R for the conjugated plane

indicates increased tilt away from the substrate, while

a more negative R for the long axis indicates greater

surface-normality.

We observe four distinct orientation regimes during

annealing, as shown in Figure 3. First, the precursor is

vertically oriented, and this weak orientation persists

until the treatment temperature of 125 °C exceeds the

melting point at 110 °C. Second, R decreases from

125 °C to 150 °C. Third, R increases greatly between

150 °C and 200 °C, where the greatest increases in ester

thermolysis are also observed, to plateau at 200 °C. At

this point, both the conjugated plane and the long axis of

the molecule are angled away from the surface as depicted

in Figure 2. Finally, R decreases again at 300 °C indicating

that the molecules relax into a more disordered orientation.

This relaxation corresponds to coverage loss, which was

also quantified with NEXAFS spectroscopy.

Figure 4: Graphical representation of the relationship between

the degree of conversion and molecular orientation with the field

effect mobility in a transistor device.

This example highlights NEXAFS as a powerful,

nondestructive technique for detailed quantification of

the structure and chemistry of nanometer thick organic

semiconductor films. These data provided insight into,

and direct correlations with, the changes in electronic

properties. NEXAFS will continue to provide a

powerful measurement platform for the systematic

investigation of organic semiconductors and conductors.

For More Information on This Topic

D.M. DeLongchamp, S. Sambasivan, D.A. Fischer,

E.K. Lin, P. Chang, A.R. Murphy, J.M.J. Frechet,

and V. Subramanian, “Direct Correlation of Organic

Semiconductor Film Structure to Field-Effect Mobility,”

Advanced Materials 17, 2340–2344 (2005).

Technical Highlights
4

Chaotic Flow to Enable Soft Nanomanufacturing

intersecting channels is a cross flow mixer (CFM) as

shown in Figure 1. To generate chaos in this geometry,

flow in the two perpendicular channels of the cell is

driven sinusoidally, and 90 ° out of phase. Thus,

successive sets of temporal streamlines cross each other

every quarter period at the center of the geometry, as

required for chaos per the crossing streamline principle.

Conventional methods fail in the analysis of

chaotic flow. Thus, in order to evaluate the ability

of a flow configuration to produce chaotic motion,

the deformation of material lines or surfaces composed

of passive tracer particles are tracked in a manner

analogous to flow experiments using tracer dyes.

The deformation of a material line composed of 25,000

individual particles in the CFM is shown in Figure 1.

The material line is initially stretched out along the

x-axis (Figure 1a), and the stretching and folding of the

material line gradually leads to the particle dispersion

pattern shown in Figure 1d.

From the deformation of the material line, we may

identify three signatures of chaos. First, from the figure

we see that the particles tend to evolve to a formation

in which they are randomly dispersed in a closed

surface within the flow domain — this is a signature

of Hamiltonian chaos. A second signature is the

exponential stretching of the line of particles. A semilog plot of L/L0 vs. time (where L is the length of the

line) shows that the data are very closely fit by an

exponential relationship with a positive exponent value

of 0.41, which can be thought of as an “effective” or

Technical Highlights

The challenge of generating nanoscale functional

structures from soft materials (polymers, colloidal

suspensions, dispersions) requires innovative

manufacturing strategies. In our program, we utilize

microfluidics to combine self-assembly technologies

with top-down manufacturing methods. Proper

mixing of components emerges as a crucial issue in

microfluidic manufacturing operations due to the

breakdown of conventional techniques. Our objective

is to utilize the concept of “chaotic flow” for proper

mixing of components.

Frederick R. Phelan, Jr. and Steve Hudson

Acentral goal of nanomanufacturing is to combine

 top-down manufacturing techniques with bottom-up

methodology in a flexible and robust fashion. We are

developing a portfolio of microfluidic-based techniques

to accomplish this objective, focusing on particle

self-assembly and in-situ monitoring of manufacturing

operations.

An outstanding issue in a wide variety of

manufacturing operations is the efficient mixing of

liquid phase chemical species. Due to the small length

scales of the flow channels (from 1 μm to 200 μm),

the typical turbulent mixing, which is extensively

utilized in larger scale flows, cannot be achieved, and

new schemes must be developed. It is known that

chaotic flow is the most efficient way of mixing outside

the turbulent regime. In microfluidics, little is known

about how to generate chaotic flow and how to best

measure it. Here we describe numerical methodologies

that demonstrate chaotic flow in microfluidic

geometries. We find the signatures of chaos via

detailed analysis of the flow fields and show that we

can generate chaotic flow for both pressure-driven

and electric field-driven flows.

To generate chaos in microfluidic flows, we exploit

the principle of temporally crossing streamlines which

states that a necessary condition for generating chaotic

flow is that the streamlines at time t must intersect the

streamlines at some later time t + ∆t at one or more

points in the flow domain. The crossing streamlines

considered in this work are distinctly different from

those considered in previous studies. We considered

here the case of flow in intersecting channels, where

temporal variations are introduced through the use of

oscillatory flow boundary conditions.

Both batch and continuous mixing have been

studied, as they both have direct relevance to processes

of interest. For batch mixing, the simplest case of

Figure 1: Chaotic mixing in a pressure-driven cross flow mixer

(CFM), for a Strouhal number of 1.28 after 15 cycles. A material

line composed of 25,000 particles is initially stretched out along

the x-axis. The stretching and folding of the material line leads to

kinematic particle dispersion, a signature of chaotic flow.
5

finite-time Lyapunov exponent. A final signature of

chaos is that the flow is ergodic — that is, the dispersion

patterns observed after a large number of cycles for

different particle initial conditions are indistinguishable

from one another. Simulations with different particle

initial conditions confirm the ergodic property.

The onset of chaotic behavior in the CFM is

controlled by a dimensionless number called the

Strouhal number (St) which relates the distance a

particle moves in a half-cycle to the width of the flow

channel. Chaos sets in at St ≈ 0(1), and the size of the

chaotic region and magnitude of the Lyapunov exponent

grows continually with increasing St. Further, we

identified that the mechanism for chaotic flow in the CFM

is a periodic combination of stretching and rotation,

making the system a continuous tendril-whorl (TW)

type flow. This differentiates it from other studies using

oscillatory boundary conditions as they produce discrete

(non-continuous) TW flows resulting in the requirement

of greater geometric complexity to mix the fluid streams.

Clearly, the configuration may also be used with a

discontinuous throughput stream, to mix components

on a semi-batch basis.

The results discussed above are for pressure-driven

flow. However, an important means of transporting

fluid in microfluidic geometries is through the use of

electroosmotic flow (EOF), especially in the emerging

area of droplet-based microfluidics. In the EOF flows,

temporally crossing streamlines are generated by

application of out-of-phase sinusoidal voltage gradients.

We find that chaotic mixing can also be obtained in

EOF, for both batch and continuous flow. Stretching of

a material line for batch mixing via EOF is shown in

Figure 3a and for continuous mixing in the star-cell

in Figure 3b. Chaotic particle dispersion and positive

Lyapunov exponents are observed for both cases.

In terms of experimental implementation, the EOF

driven flow offers several advantages. First, the ends

of the oscillatory channels are closed, so there are no

inflow and outflow to handle. Second, the oscillatory

flow channels can be made shorter for EOF, as it was

found that the critical Strouhal number for the onset of

chaos decreased and the effective Lyapunov exponent

increased, as the ratio of the length to the width of

these channels was made smaller.

Experimental testing of these results is currently

being conducted as well as an investigation of the

interplay between diffusion and chaotic flow.

For More Information on This Topic

F.R. Phelan, Jr., N.R. Hughes, and J.A. Pathak,

“Analysis of the Mechanism for Chaotic Mixing in

Oscillatory Flow Microfluidic Devices,” submitted to

Phys. Rev. Lett., 2005.

F.R. Phelan, Jr., N.R. Hughes, and J.A. Pathak,

“Mixing in Microfluidic Devices Using Oscillatory

Channel Flow,” submitted to Physics of Fluids, 2005.

Figure 2: Chaotic mixing in the star-cell geometry is shown for

a Strouhal number of 1.28 and a velocity ratio of 0.125 after

10 cycles. In the star-cell, chaos is generated by the oscillatory

flow in transverse channels, and the lateral flow provides

throughput for continuous mixing.

Figure 3: a) Chaotic mixing in an EOF driven cross-flow

mixer (CFM), for a Strouhal number of 0.64 after 10 cycles.

b) Chaotic mixing in an EOF driven star-cell mixer, for a Strouhal

number of 2.04 and a velocity ratio of 0.125 after 10 cycles.

For both cases, the oscillatory flow is driven by the application

of out-of-phase sinusoidal voltage gradients along the major

axes of the cell.

Technical Highlights

We now discuss continuous chaotic mixing,

which will be relevant to any continuous high-speed

nanomanufacturing operation. In a configuration

called the star-cell geometry (see Figure 2), a lateral

continuous channel flow (from left to right) is

combined with the oscillatory cross flow. The mixing

characteristics in the star-cell are a function of both

St and the ratio of the continuous-to-oscillatory velocity.

The deformation of a material line passing through the

oscillatory section is shown in Figure 2. The particle

dispersion in the downstream channel indicates that

the competition between the two flows is quite

effective in producing a well-mixed effluent.
6

X-ray Reflectivity as a Tool for Characterizing Pattern Shape

and Residual Layer Thickness for Nanoimprint Lithography

Nanoimprint lithography has the potential for high

throughput patterning with an ultimate resolution

of better than 10 nm. With these length scales,

our ability to pattern greatly exceeds our ability to

quantitatively evaluate the quality of the patterning

process. Measurements that can evaluate the fidelity

of the pattern transfer process and the overall quality

of the imprint are critical for realizing the full

potential of nanoimprint patterning techniques.

Christopher L. Soles and Ronald L. Jones

Nanoimprint Lithography (NIL) is a form of printing

whereby nanoscale features are written into a

master, typically Si, quartz, or some other hard material,

using a slow, high-resolution technology such as

e-beam lithography. The master can then be rapidly

and repeatedly stamped into a softer resist film. This

replication technique is a cost-effective way to combine

the high-resolution patterning of e-beam lithography

with the throughput of a stamping or printing process.

Figure 1: Schematic of nanoimprint lithography process.

The resolution of NIL is comparable to that of e-beam

lithography, and features as small as 10 nm have been

demonstrated. However, it is difficult to quantify and

control dimensions in such small features. To take

full advantage of the potential resolution of NIL, highresolution shape metrologies are critical. Furthermore,

during the imprint process, the master is unable to fully

displace the resist and make contact with the substrate.

This leaves a residual layer of resist between the features

that can be removed with a reactive ion etch. However,

this also laterally erodes the feature width. Minimization

of this lateral trimming and control of the final feature

size requires a precise knowledge and optimization of the

residual layer thickness. In short, two of the most pressing

issues facing NIL include: (1) quantifying the fidelity

with which the patterns in a master are transferred to

the imprinted film; (2) quantifying the residual layer

thickness. Here we adapt specular x-ray reflectivity

(SXR) to quantify both the fidelity of pattern transfer

and the residual layer thickness with nanometer

precision in NIL masters and patterns.

SXR is a well-established method for measuring both

the thickness and the density as a function of depth into

a thin film. Here we extend the use of SXR to patterned

films where the lateral length scales of the patterns are in

the sub μm range. As the cartoon in the inset of Figure 2

indicates, the master or mold is comprised of a single

material, SiOx (black). However, the reflectivity, R, is

characteristic of a bilayer film, a smooth “gray” film

on the black SiOx. The strong, periodic Kiessig fringes

and the two critical angles Qc are consistent with a

smooth bilayer structure. The red line through the blue

experimental data points is a fit to such a smooth bilayer

model where the density of the gray layer is an average

of the white and black (open and fully dense) regions of

the pattern while the thickness of the gray layer equals

the pattern height. The SXR averages density over

length scales that are apparently larger than the

lateral-length scales of the topology.

Figure 3: SXR data from a polymeric resist imprint created from

the master characterized in Figure 2.

Figure 2: SXR data from a NIL master. Q=2π/λ sin(θ) with λ

the wavelength of the incident radiation and θ the grazing angle.

Technical Highlights
7

Analogous SXR measurements are repeated on

a polymeric resist imprint created from the master above.

These reflectivity data are shown in Figure 3. Consistent

with the mold, the reflectivity from the imprint on the

SiOx substrate shows characteristics of a smooth trilayer

structure. The Kiessig fringes show a beating of multiple

periodicities, and three Qc’s are observed. The cartoon in

the inset indicates black for the SiOx substrate, dark gray

for the pure resist, and light gray for the patterned region

of the resist. As before, the light gray is an average

of the dark gray (solid) and white (open) domains.

The red solid line through the blue experimental data

is a quantitative fit to a smooth trilayer model.

here. Through these density variations as a function of

pattern height, the pattern cross-sections can be evaluated.

The scattering length density Qc

2 profiles as a

function of distance vertically through the patterns (z)

are shown in Figure 4. Qc

2 is directly proportional to

mass density, and the horizontal dotted lines indicate the

values of Qc

2 for the pure SiOx and the resist. On the

density profile for the imprint, the region (1281 ± 10) Å

wide matching the full density of the resist represents

the residual layer thickness. To the left of this is a

region of reduced density that is (1730 ± 10) Å wide.

This is the height of the pattern. One can also see how

the depth of the patterns in the mold equals the height of

the imprinted pattern; this indicates complete mold fill.

Such a comparison of the mold and imprint can be used

to quantify the fidelity of pattern transfer.

There are two blue vertical arrows drawn next to the

profile of the imprint. Line “l” starts at Qc

2 = 0 and extends

vertically to the intersection of the imprint profile. Line

“s” starts at this same intersection and extends vertically

to the Qc

2 value corresponding to the density of the pure

resist. At any z, the ratio l:s defines the line-to-space ratio

of the pattern. This ratio increases with z for the imprint,

indicating that the pattern is narrow on the top and

broadens near the residual layer. A similar construction

can be made for the mold although the lines are not shown

Figure 5: Comparison of mold and imprint profiles. The red and

blue data points indicate the line shape profiles from the SXR for

the mold and imprint, respectively. The corresponding physical

models that best fit the data are indicated by the solid lines. For

the sake of clarity, the mold data are shown on the left side of one

of the features while the imprint data are shown on the right.

These line width variations as a function of pattern

height are relative, and one cannot define an absolute

line width from the SXR alone. An external calibration

of the line width, space width, or pattern pitch is needed

to convert the relative line-to-space variations into

absolute values. To illustrate this, critical-dimension

small angle x-ray scattering (CD-SAXS) was used to

quantify the pattern cross-section. A trapezoidal line

shape provided an excellent fit to the CD-SAXS data.

Figure 5 is the resulting comparison that shows how

well the imprint features fit into the mold, indicating an

excellent fidelity of transfer. The pitch of 1945 Å from

the CD-SAXS models is used to transform the relative

line-to-space ratios from the SXR density profiles into

physical line widths. These SXR data points exactly

coincide with the solid lines for the CD-SAXS models,

showing excellent agreement in terms of both pattern

height and the trapezoid side wall angles β.

In summary, SXR is a powerful metrology to

quantitatively characterize the residual layer thickness

and the relative line-to-space ratio variations as a

function of pattern height. If one of the widths (line

or space) or pattern pitch is known by some other

technique (CD-SAXS, SEM, AFM, etc.), these relative

line-to-space ratios can be quantified in terms of an

absolute length scale to completely define the pattern

cross-section. Applying this metrology to both the

mold and the imprint makes it possible to not only

quantitatively measure the residual layer thickness

but also assess the fidelity of pattern transfer.

For More Information on This Topic

H.J. Lee, C.L. Soles, H.W. Ro, R.L. Jones, E.K. Lin,

W.L. Wu, and D.R. Hines, Appl. Phys. Lett. 87, 263111

(2005).

Figure 4: Scattering length density profiles as a function of

distance vertically through the patterns for the mold (red) and the

imprint (blue). The horizontal axis is arbitrarily assigned, so the

mold substrate on the left (≈ 0 Å) faces the imprint substrate on

the right (≈ 3100 Å) with the mating pattern region in between.

Technical Highlights
8

Gradient Libraries of Surface-Grafted Polymers:

Combi Tools for Surface Functionality

Advanced applications, such as friction and

wear management in microelectromechanical

systems (MEMS), adhesion promotion for coatings,

protein adsorption control in biomaterials, and

environmentally responsive surfaces for sensors

require tunable, well-defined interfaces. Layers

of grafted polymers provide means for physically

robust, chemically versatile surface functionalization.

While recent advances in controlled polymerization

enable grafted polymers that exhibit many types

of architecture and composition, identifying the

optimal grafted system for a given application

can be difficult, time consuming, and expensive.

Kathryn L. Beers and Chang Xu

Through the NIST Combinatorial Methods Center

(NCMC), the Polymers Division has developed

new tools for probing the optimal molecular- to

micro-scale properties of grafted polymer systems.

These methods employ microfluidic technology to

deliver tailored mixtures and sequences of monomers

to an initiator-functionalized surface. The resulting

grafted polymer libraries exhibit gradual, systematic

changes in composition, chain length, and architecture.

Gradients of grafted block copolymers prepared via

these techniques reveal composition regimes that

“switch” their surface properties in response to solvent

exposure. Moreover, our unique method for preparing

statistical copolymer composition gradients provides

comprehensive maps of complex surface chemistry

that were previously impossible.

Using shallow channels (< 500 μm in height) to

confine fluids over initiator-functionalized surfaces

suppresses mixing. By controlling the composition

of fluids pumped into the channels, and the length of

time of surface exposure, gradients in composition or

relative molecular mass are produced. This technique,

micro-channel confined surface initiated polymerization

(μSIP), was used to produce a variety of combinatorial

surfaces as shown in Figure 1 and enables systematic

measurement of polymerization parameters.

Figure 2: A) Film thickness of gradient poly(n-butyl methacrylate)

(pBMA) homopolymer (closed symbols) and poly(n-butyl

methacrylate-b-N,N-dimethylaminoethyl methacrylate)

(p(BMA-b-DMAEMA)) (open symbols). B) Percentage growth of

PDMAEMA block on the gradient surface with respect to a bare

initiator-modified surface.

Figure 1: Examples of polymer libraries prepared using

micro-channel confined surface initiated polymerization (μSIP)

and ATRP of methacrylates.

The initiation efficiency of a homopolymer on a

surface affects both the density and relative molecular

mass distribution of the second block that can be

grown from it. Figure 2A shows data from a relative

molecular mass gradient of poly(n-butyl methacrylate)

(pBMA) that was uniformly chain extended with

poly-(N,N-dimethylaminoethyl methacrylate)

(pDMAEMA) to form the block copolymer poly(n-butyl

methacrylate-b-N,N-dimethylaminoethyl methacrylate)

(p(BMA-b-DMAEMA)).

A relative measure of initiation efficiency was

obtained as a function of molecular mass of the bottom

pBMA block by normalizing the change in thickness of

p(BMA-b-DMAEMA) to the thickness of pDMAEMA

grafted directly from a separate initiator-functionalized

surface. The data in Figure 2B show that the efficiency

remains above 90 % for pBMA with a thickness of 15 nm

or less, indicating that comparative measurements of

block copolymer behavior are possible below this

thickness. Using this information, a series of surfacegrafted block copolymer gradients was prepared with

pBMA as the bottom block and pDMAEMA as the

top block.

Figure 3A shows data from three gradient surfaces with

different, uniform bottom block thicknesses and similar

gradients in top block thickness. The surface energy, as

Technical Highlights
9

measured by water contact angles, of the air interface

of the brush layer can be controlled by exploiting

solubility differences between pBMA and pDMAEMA.

In water, the pDMAEMA chain segments swell, while

the pBMA segments collapse. After drying, the surface

exhibits the same water contact angle as pDMAEMA

homopolymer brushes as long as there is at least

(2 to 3) nm of pDMAEMA in the copolymer to cover

the surface (Figure 3B, open symbols). After exposure

to hexanes, which will swell the lower pBMA chain

segments and collapse the pDMAEMA segments,

the pBMA segments can be expressed at the surface,

covering the pDMAEMA segments. The main

requirement for this “surface response” is a ratio

of pBMA to pDMAEMA sufficient for complete

rearrangement and pBMA surface coverage, as

shown in Figure 3B. At intermediate ratios, a partial

expression of the lower pBMA produces a range

of intermediary surface energetics.

Determination of the composition range for

this transition, its dependence on chain length, and

optimization of the response region were all possible

using the gradient method. Performing measurements

on single gradient specimens reduced variability and

illuminated the subtlety and sensitivity of the transition

to relative molecular mass and copolymer mass fraction.

Well-defined surface chemistry has been used to

control structure formation in thin films and fluid flow in

microfluidic devices. To map and optimize these effects,

controlled, smooth gradients in chemical expression have

been produced with self assembled monolayers (SAMs).

However, SAM surfaces offer a limited number of

functional groups and modest stability over time. Polymer

brush layers provide means to expand the chemical

diversity of surface gradients while creating a layer of

carbon chains to protect the hydrolytically unstable silicon

oxygen bonds that covalently link the chains to the surface.

A compelling case is a gradient in statistical copolymer

composition, for which we have recently developed a

fabrication strategy using μSIP.

Figure 4: A) Stability of a monomer composition gradient

inside a microchannel monitored by Raman spectroscopy at 0 h

(black squares) and 2 h (red circles). B) Water contact angle of

p(BMA-co-DMAEMA) as a function of position on a gradient

of composition prepared from the solution gradient mapped

in Figure 4A.

A gradient in solution composition was

constructed such that the monomer feed was varied

from (2 to 98) % by volume DMAEMA relative

to BMA along the channel (Figure 4A). Both the

establishment and stability of the solution gradient

were measured by Raman spectroscopy, indicating

that the gradient persisted for at least 2 h, while the

reaction time was only 40 min. Figure 4B shows

water contact angle measurements taken along

the polymerized gradient, which reveal a smooth

transition from the surface energetics characteristic

of pDMAEMA to those of pBMA. The changing

composition of the polymer brush was also

characterized by NEXAFS measurements (data not

shown). Unlike the block copolymers, the statistical

copolymer surface does not switch the surface

expression with exposure to different solvents.

The chemical gradient is trapped by the intimately

mixed nature of the copolymerization.

Fabrication of grafted tapered copolymers,

which exhibit a gradual change in composition

along the polymer chain, has also been demonstrated.

An upcoming publication will describe the fabrication

and properties of this unique system. In addition,

future work includes combining micro-scale patterning

with the chemical gradient brushes for the fabrication

of calibration specimens, as well as expanding

the method to additional monomer types and

polymeriziation mechanisms to make μSIP a

versatile, widely applicable measurement tool.

For More Information on This Topic

C. Xu, T. Wu, C.M. Drain, J.D. Batteas, and

K.L. Beers, Macromolecules 38, 6–8 (2005).

C. Xu, T. Wu, J.D. Batteas, C.M. Drain, K.L. Beers,

and M.J. Fasolka, Appl. Surf. Sci. 252, 2529–2534 (2006).

Or visit the NCMC website (www.nist.gov/combi)

Figure 3: A) Thickness profiles of three gradient surfaces of

p(BMA-b-DMAEMA) prepared via μSIP. B) Solvent response

behavior of p(BMA-b-DMAEMA) in water (open symbols) and

hexanes (closed symbols) as a function of relative molecular

mass of the top (pDMAEMA) block for three thicknesses of pBMA

bottom block. Colors and symbols correlate solvent response

profiles to samples mapped in Figure 3A. Lines drawn to aid

reader’s eyes.

Technical Highlights
10

Quantifying Cellular Response to Biomaterials with

Macromolecular Assembly

In order to move beyond empirical trial and error

into design, biomaterials development is in urgent

need of reliable measurement standards and

techniques. These depend on the ability to quantify

protein-mediated cellular response to technologically

relevant materials. We introduce a multi-molecular

assembly of polymer/protein gradients as a technique

to do just that. We demonstrate its potential to

study interactions between fibroblasts, a particular

polymeric biomaterial, and fibronectin. However,

we emphasize the ease of extending the technique

to quantify interactions between a variety of

biomedically relevant polymers, proteins, and cells.

Ying Mei, Lori Henderson, and Jack R. Smith

The competing issues of reproducibility and

applicability in measurements of cellular response

must be addressed by the biomaterials industry.

Information generated by experimental testing needs

to be quantitatively robust, however, the inherent

variation in the response of any biological organism

and the complexity of protein/surface interactions are

problematic; most currently used biomaterials lack a

homogeneous or well-determined surface; efforts to

quantify biological response have focused on using

regular and simplified model surfaces, such as those of

self-assembled monolayers (SAMs); and the fact that

polymers of direct interest in biomedical applications

cannot be incorporated into SAMs renders the practical

applicability of these results questionable.

To address these issues, we synthesized a surface

incorporating a biomedically relevant polymer,

poly(2-hydroxylethyl methacrylate) [poly(HEMA)],

through a multi-macromolecular assembly (MMA).

We use automated fluorescent microscopy to

demonstrate that the system is sufficiently well-defined

for quantifiably repeatable measurements of cell

response and protein adsorption. We have described

the latter phenomenon to a high degree of accuracy

with a simple, geometric model.

Preparation of the MMA gradient sample is

conceptually simple. First, a SAM of octyltrichlorosilane

(OTS) is deposited on a silicon substrate by evaporation.

Then, the wafer is placed upright in a reaction vessel

where atom transfer radical polymerization (ATRP)

initiator is pumped in at a specific rate (Figure 1a).

Filling from the bottom creates a differential exposure

to the initiator along the length of the sample parallel

with the walls of the vessel. This leaves a grafting

density (σ) gradient of poly(HEMA) on the surface of

Figure 2: FN density vs. σ. Black data points are averaged

results from three gradient or twelve uniform (non-gradient)

samples. FN density was estimated from measurements of the

thickness of the adsorbed layer obtained via ellipsometry.

Data in red were obtained from the geometric model of

poly(HEMA) surface coverage.

Figure 1: A) Schematic illustration of the reaction vessel used

in the preparation of the gradient of polymerization initiator.

B) Schematic illustration of poly(HEMA) conformational change

from “mushroom” regime to “brush” regime on the gradient

surface. Poly(HEMA) is represented in black, while FN is

schematically represented by the multi-colored structures.

OTS is represented as an unfilled rectangle. ATRP initiator

is represented as a gradually filled rectangle.

the sample in the direction parallel to the walls of the

reaction vessel (Figure 1b). Subsequently, the sample

is removed from the vessel and exposed to fibronectin

(FN) solution. Later, the samples are seeded with

fibroblast NIH-3T3 cells in medium.

Technical Highlights
11

Although combinatorial studies have already received

significant attention in biomaterials research, their use

is limited by the lack of a complete toolbox including

streamlined sample preparation, characterization,

bioactivity assay, and data analysis. We demonstrate

the uses of gradient preparation technology, controlled

cell culture, automated fluorescence microscopy and

quantitative image analysis to generate a database for

combinatorial investigation of the effect of σ on cell

adhesive protein adsorption, fibroblast adhesion,

and spreading.

In addition, adsorption profiles of different

biological macromolecules and their interactions

with surface chemistries can be quantified by

simply replacing FN in the pre-adsorption part

of this experiment. In fact, we are currently

using the approach presented here to investigate

poly(HEMA)/fibrinogen gradients and will do so

with other extracellular matrix proteins. MMA has

few limitations regarding the variety of cells in the

experiment; therefore the combination of MMA

technology, quantitative fluorescence microscope,

and controlled cell culture provides the foundations

for the cell informatics about material properties,

protein adsorptions, and cellular responses.

Reference

1. S.J. Sofia, V. Premnath, and E.W. Merrill,

Macromolecules 1998, 31, 5059.

For More Information on This Topic

Y. Mei, T. Wu, C. Xu, K.J. Langenbach, J.T. Elliott,

B.D. Vogt, K.L. Beers, E.J. Amis, and N.R. Washburn,

Langmuir 21, 12309–12314 (2005).

Figure 4: a) Histogram of cell size on various FN coated

surfaces: bare OTS (green), low (red), high (blue, purple).

b) Inset: Change in cell spreading (area) with σ.

FN adsorption (FNads), measured using variable

angle spectroscopic ellipsometry, was found to vary

sigmoidally with σ (Figure 2). A simple geometric

model, in which FNads is proportional to the area of the

surface left uncovered by polymer, predicted the former

with a r2 coefficient of 0.97 (Figure 2). In the model,

the surface coverage of poly(HEMA) is estimated from

σ obtained from ellipsometry measurements performed

prior to FN exposure and the radius of gyration of

poly(HEMA).[1]

Figure 3: Fluorescence microscopy image of stained fibroblast

NIH-3T3 cells seeded on a FN pre-coated σ gradient sample.

Although the sample is contiguous, its microscopy image here is

split into three segments so that changes in cell morphology with

distance/σ will be visible on the page. Distance in the Figure

is measured from the end of the sample closest to the top of the

reaction vessel (i.e., from the end of the sample with lowest σ)

in Figure 1a.

Cellular response varied dramatically along the

surface of the poly(HEMA)/FN gradient (Figure 3).

As cell spreading (Figure 4) and FNads (Figure 2) were

both found to vary sigmoidally with σ, the high degree

of correlation between the two phenomena was clearly

demonstrated. The onset of maximal cell adhesion and

cell spreading were measured at FNads of 50 ng/cm2

and 100 ng/cm2, respectively. Further, a ten-fold

increase in σ caused a change in the average area of

fibroblasts (i.e., cell spreading) from (1238 ± 704 to

377 ± 216) μm2. The standard deviation represents

the variation of the measurement over 12 trials.

Results obtained on three separate gradient

samples were in quantitative agreement with those

obtained on uniform (i.e., non-gradient) samples of

similar composition (Figure 2 and 4). This shows

the capability of the former to dramatically advance

the pace of biomedical materials research through

simultaneous testing of multiple compositions.

Technical Highlights
12
13

Program Overview

Nanometrology

Nanotechnology will revolutionize and possibly

revitalize many industries, leading to new and improved

products based on materials having at least one dimension

less than 100 nm. The federal government’s role in

realizing the full potential of nanotechnology is coordinated

through the National Nanotechnology Initiative (NNI),

a multi-agency, multi-disciplinary program that supports

research and development, invests in a balanced

infrastructure, and promotes education, knowledge

diffusion, and commercialization in all aspects of

nanoscale science, engineering, and technology.

NIST’s unique and critical contribution to the NNI is

nanometrology, defined as the science of measurement

and/or a system of measures for nanoscale structures

and systems. NIST nanometrology efforts focus

on developing the measurement infrastructure —

measurements, data, and standards — essential to

advancing nanotechnology commercialization.

This work provides the requisite metrology tools

and techniques and transfers enabling measurement

capabilities to the appropriate communities.

MSEL plays a vital role in nanometrology work at

NIST with efforts in four of the seven NNI Program

Component Areas — Instrumentation Research,

Metrology and Standards for Nanotechnology;

Nanomaterials; Nanomanufacturing; and Fundamental

Nanoscale Phenomena and Processes. Innovative

projects across MSEL are defining and addressing

the forefront research issues in these areas.

Instrumentation Research, Metrology

and Standards for Nanotechnology

R&D pertaining to the tools needed to advance

nanotechnology research and commercialization.

The design, development, and fabrication of nanodevices

will require nanomechanical measurements that are rapid,

accurate, predictive, well-understood and representative

of a device or system’s environment in real time. MSEL

is addressing this need by developing instrumentation,

methodology, reference specimens and multi-scale

modeling approaches to quantitatively measure mechanical

properties such as modulus, strength, adhesion, and

friction at nanometer-length scales. This year, novel

instruments for measuring adhesion and friction forces

between surfaces and nanoparticles were developed jointly

with industrial partners. Quantitative maps of elastic

modulus were obtained by innovative methodologies based

on atomic force microscopy and strain-induced elastic

buckling instability. To address the need for quantifying

measurements made with widely-used commercial

nanoindentors and scanned probe microscopy

instruments, MSEL is developing reference specimens

and SI-traceable force calibration methodology.

Nanomaterials

Research aimed at discovery of novel nanoscale

and nanostructured materials and at a comprehensive

understanding of the properties of nanomaterials.

Among the many classes of nanomaterials, nanotubes

have received great attention due to their remarkable

physical properties relevant to many applications.

In response to needs expressed by industry and other

federal agencies, MSEL has embarked on a new effort

to develop a suite of metrologies and standards aimed

at characterizing key structural features and processing

variables of carbon nanotubes. These include dispersion,

fractionation, orientation, alignment, and manipulation

of individual single-walled nanotubes, all critical to

establishing efficient bulk processing schemes to meet

the imminent high demand for carbon nanotubes.

Nanomanufacturing

R&D aimed at enabling scaled-up, reliable,

cost-effective manufacture of nanoscale materials,

structures, devices, and systems. Nanoimprint lithography

(NIL) is rapidly emerging as a viable high-throughput

technique for producing robust structures with a

patterning resolution better than 10 nm. MSEL is

developing metrologies that are crucial to advancing

NIL as an industrial patterning technology for the

electronics, optics, and biotechnology industries.

The current focus is on characterizing shape and

the fidelity of pattern transfer, two key factors in

achieving widespread commercial application of NIL.

Fundamental Nanoscale

Phenomena and Processes

Discovery and development of fundamental knowledge

pertaining to new phenomena in the physical, biological,

and engineering sciences that occur at the nanoscale.

The magnetic data storage industry needs the ability to

measure and control magnetization on nanometer length

scales and nanosecond time scales to meet increasing

demands for reduced size and increased speed of devices.

MSEL is developing measurement techniques to elucidate

the fundamental mechanisms of spin dynamics and

damping in magnetic thin films. Work this year has

focused on measurements of the effects of interfaces

and interface roughness on magnetization dynamics and

magnetic characterization of edges in magnetic devices.

Through these and other research activities,

MSEL is maintaining its committed leadership in

developing the measurement infrastructure for

current and future nanotechnology-based applications.

Contacts: Alamgir Karim; Kalman Migler
14

Engineering of nanomaterials, biomaterials, and

organic electronic devices hinges on techniques

for imaging complex nanoscale features. In this

respect, new Scanned Probe Microscopy (SPM)

methods promise mapping of chemical, mechanical,

and electro-optical properties, but these techniques

generally offer only qualitative information.

Our reference specimens, fabricated with a

combinatorial design, calibrate image data from

emerging SPM methods, thereby advancing these

nanometrology tools.

Michael J. Fasolka

Anew generation of SPM techniques intend to

 measure chemical, mechanical, and electro/optical

properties on the nanoscale. However, contrast in new

SPM images is difficult to quantify since probe fabrication

can be inconsistent, and probe/sample interactions are not

understood. Our research at the NIST Combinatorial

Methods Center (NCMC) provides reference specimens

for the quantification of next-generation SPM data.

Using a gradient combinatorial design, our specimens

gauge the quality of custom-made SPM probes and

calibrate SPM image contrast through “traditional” surface

measurements (e.g., spectroscopy and contact angle).

Nanometrology

Reference Specimens for SPM Nanometrology

Figure 2: Demonstration of ∇μp specimen. SPM friction

contrast (κ) vs. surface energy (γ) differences obtained with

probes of different chemical quality. The red arrow marks the

γ-difference sensitivity of a UV-ozone cleaned probe.

Figure 1: Schematic illustration of the ∇μp for calibration of

chemically sensitive SPM techniques. Blue “droplets” illustrate

water contact angle measurement along the calibration strips.

of the matrix. Accordingly, traditional measurements,

e.g., water contact angle, along these fields relate

the chemical contrast in the ∇μp to known quantities,

e.g., surface energy differences.

Figure 2 demonstrates the utility of the ∇μp specimen

for SPM data calibration. This plot was generated from a

series of SPM friction images acquired along the graded

pattern. A frictional contrast parameter, κ, which reflects

measured friction force differences between the lines and

matrix, was extracted from each image. To create a

contrast calibration curve, κ is plotted against surface

energy data derived from water contact measurements

along calibration fields. As shown in Figure 2, the

combinatorial ∇μp provides, in a single specimen, a fullspectrum relationship between SPM friction force and

surface energy. As shown through the three curves, the

specimen also enables direct comparison between different

probe functionalization strategies. Moreover, the curves

illuminate the minimum γ-difference detectable by a given

probe (where κ → 0), i.e., its chemical sensitivity.

Our fabrication route for the ∇μp, and its use as

a reference specimen for emerging SPM techniques,

is the subject of an article published in Nanoletters

(2005, ASAP).

Contributors and Collaborators

K.L. Beers, D. Julthongpiput (Polymers Division,

NIST); D. Hurley (Materials Reliability Division, NIST);

T. Nguyen (Materials and Construction Research Division,

NIST); S. Magonov (Veeco/Digital Instruments)

This year, we demonstrated the fabrication and use

of a reference substrate that combines patterning of a

self-assembled monolayer (SAM) with a surface energy

gradient. Our gradient micropattern (∇μp) specimens

incorporate a series of micron-scale lines that continuously

change in their surface energy compared to a constant

matrix. Patterning is achieved via a new vapor-mediated

soft lithography of a hydrophobic chlorosilane SAM on

SiO2 (matrix). A subsequent graded UV-Ozone exposure

gradually changes the chemistry of the patterned SAM

along the specimen from hydrophobic to hydrophilic

species. As shown in Figure 1, the specimen design

includes two calibration fields, which reflect the changing

chemistry of the SAM lines and the constant chemistry
15

Nanometrology

Nanotube Processing and Characterization

Single-wall carbon nanotubes (SWNTs) exhibit

remarkable physical properties, and there is

considerable interest in using them as nanoscale

building blocks for a new generation of

applications. Despite this promise, fundamental

issues related to the dispersion, fractionation,

orientation, and manipulation of individual

single-walled carbon nanotubes remain unresolved,

and efficient bulk processing schemes do not exist.

We are working at the scientific front of this rapidly

emerging field to establish research protocols that

will help ensure that this new technology progresses

as quickly and efficiently as possible, but with

uniformly high standards.

Barry J. Bauer, Kalman Migler, and Erik K. Hobbie

Upon their discovery in 1991, carbon nanotubes

were recognized as ideal materials for nanotechnology

applications. Properties of carbon nanotubes differ

vastly depending on their diameter and chirality, and

interest in these materials stems from their extraordinary

combination of properties: superior thermal conductivity,

electrical conductivity, and mechanical strength.

Nanotubes are thus attracting great attention for

emerging technologies such as bio-chemical sensors,

next generation displays, and nano-electronics.

Regardless of the ultimate applications, nanotubes

clearly represent the most important new class of

materials in the past 15 years.

However, application development is plagued by

inconsistent sample quality, compounded by a lack of

consensus on material characterization methods and by

poor measurement reproducibility. The quality

problems plaguing the nanotube community were

described in a recent news article in Nature which

stated, “the situation will not improve until an external

body introduces standards that suppliers can follow.”

Few people were surprised by the conclusion of the

recent workshop: NIST must take the lead in a

quantitative nanotube metrology that will allow

suppliers and customers to develop standards for

the developing industry.

The Nanotube Processing and Characterization

Project within the Polymers Division is actively engaged

in this effort. As a starting point, we are currently using

small-angle neutron scattering (SANS) to quantify the

degree of SWNT dispersion using a variety of dispersion

chemistries (Figure 1) and, in doing so, have identified

DNA wrapping as desirable for the purpose of fractionating

SWNTs by length, diameter, chirality, and band structure.

Figure 2: Refractive index and viscosity as a function of elution

time in a size-exclusion chromatograph from DNA wrapped

SWNTs, showing clear separation by length.

Figure 1: Measured SANS profiles obtained for two different

SWNT dispersion chemistries, showing how DNA wrapping

provides superior dispersion to other methods, such as chemical

functionalization.

Taking this one step further, we have begun using

size-exclusion and ion-exchange chromatography to sort

SWNTs by length and chirality (Figure 2). Following

the protocol pioneered by DuPont researchers, we are

producing ultra clean SWNT fractions that will be

characterized with a broad suite of NIST metrologies.

These results will in turn be used to establish universal

scientific standards for SWNT purity and dispersion.

Contributors and Collaborators

W. Blair (Polymers Division, NIST); A. Hight

Walker (Optical Technology Division, NIST);

T. Yildirim (NIST Center for Neutron Research);

M. Pasquali (Rice University); M. Zheng (DuPont)
16

Combinatorial Adhesion and Mechanical Properties

Traditional methods for evaluating the engineering

properties of polymers are time-consuming and

inherently single specimen tests. Current market

drivers increasingly demand rapid measurement

platforms in order to keep pace with competition

in the global marketplace. In this project, we are

delivering innovative combinatorial and highthroughput (C&HT) tools for the physical testing

of materials, built around measurement platforms in

the NIST Combinatorial Methods Center (NCMC).

Christopher M. Stafford

Our current C&HT efforts in this project are

concentrated in two main areas: buckling mechanics

for thin film mechanical measurements and adhesion

testing platforms for probing interfacial adhesion and

fracture. Here, we highlight: (1) the inversion of our

buckling-based metrology to study the mechanical

response of soft polymer gels, (2) the application of

finite element analysis to study buckling in multilayer

geometries, and (3) the implementation of our

combinatorial edge delamination test to study the

interfacial adhesion strength of epoxy films.

of our buckling-based technique is that a “modulus map”

can be constructed by measuring the buckling wavelength

as a function of spatial position.

Figure 1: Elastic modulus of model PDMS gels measured via

buckling (■ — gradient modulus specimen, ▲ — single specimens)

and via tensile test (● ).

In addition to our experimental efforts, we are also

utilizing finite element analysis (FEA) to help guide

experimental design in our buckling-based metrology

by verifying the validity of available analytical solutions

when applied to more complex specimen geometries.

For example, we examine a composite film consisting

of a soft layer confined between two stiff layers. In

Figure 2, FEA reveals a critical modulus ratio below

which shear deformation becomes significant, thus the

standard analytical solution can no longer be applied

to measurements in this regime.

As part of the NCMC, we have launched a Focus

Project aimed at developing a C&HT measurement

platform for testing interfacial adhesion and fracture in

thermally cured epoxy materials. This method is based

on the modified edge-liftoff test.[2] In this Focus Project,

we are building capabilities to evaluate the governing

parameters for interfacial delamination and reliability

by fabricating suitable gradient libraries in composition,

thickness, temperature, and applied stress. Industrial

sponsors for this Focus Project are ICI National Starch

and Intel Corporation.

1. C.M. Stafford, et al. Nature Materials 3, 545 (2004).

2. M.Y.M. Chiang, et al. Thin Solid Films 476, 379 (2005).

Contributors and Collaborators

M.Y.M. Chiang, S. Guo, J.H. Kim, E.A. Wilder,

W. Zhang (Polymers Division, NIST); Daisuke Kawaguchi

(Nagoya University); Gareth Royston (University of

Sheffield)

Figure 2: Normalized wavelength versus modulus ratio of a

tri-layer thin film. E2 and E1 are the moduli of the soft and stiff

layer, respectively. The solid line is the analytical solution.

Nanometrology

This year, we applied our buckling-based metrology[1]

to measure the elastic modulus of soft-polymer gels. Elastic

modulus is an important design criterion in soft polymer

gels for biomedical applications since it impacts critical

properties such as adhesion, swelling, and cell proliferation

and growth. Leveraging our C&HT buckling-based

metrology, we can rapidly assess the elastic modulus of

polymer gels by inverting the experimental design: the

buckling of a sensor film of known modulus and thickness

reports the elastic modulus of the substrate, Es. Figure 1

illustrates the accuracy of our approach as compared to

traditional tensile tests on the same material. One advantage
17

Soft Nanomanufacturing

assembly applications, image analysis was replaced by

embedded electronic sensors that detect the presence of

a particle and its size (Figure 1). This electronic signal

activates a valve to isolate a set of particles. Electronic

detection is further advantageous because it is readily

scalable to smaller particles. In comparison to previous

systems, the valves we have developed are also

advantageous, since they are not limited to shallow

channel profiles.

Figure 1: Inline particle characterization and counting. In the

image, a polystyrene particle is seen passing electrodes (dark).

At right is shown a bimodal size distribution of liquid drops

produced at a T-junction upstream.

Figure 2: Tubular structures (right) arise from the simulated

organization of triangular arrangements of dipole particles,

shown schematically at left.

High-throughput sensing and processing methods

require precision flow design and control, such as we

demonstrated and reported previously by a microfluidic

analog of the four-roll mill. Advancing beyond, we

developed a framework for generating chaotic flow

in microchannels (described in a separate highlight).

Theoretical simulations probe the organization of

geometrically and electrostatically asymmetric target

particle arrangements (Figure 2). These demonstrate

the relationship between particle symmetry and

organized structure. Depending on this symmetry,

the assemblies exhibit filaments, sheets, tubes and

icosahedra. Whereas ordinary phase separation

is driven by attractive and repulsive interactions,

self-assembly of more complex and finite-sized

structures requires directional interactions.

Of consequence for sensor applications, organization

kinetics were also investigated. In particular, nucleating

agents were found to control the kinetics of assembly

and, in polymorphic systems, to specify unique

structure.

Contributors and Collaborators

F. Phelan, Jr., J. Douglas, K. Migler, H. Hu, P. Stone,

J. Taboas, K. VanWorkum (Polymers Division, NIST);

Y. Dar, S. Gibbon (ICI/National Starch); M. McDonald

(Procter & Gamble); D. Discher, V. Percec (University

of Pennsylvania); R. Tuan (NIH)

Nanomanufacturing is widely noted as a central

challenge of nanotechnology. In the realm of soft

materials and suspended particles, it is necessary

to design particle interactions, manipulate

self-assembly processes, and measure what is

produced. Guided by theoretical simulations,

we are therefore developing high-throughput

microfluidic methods for particle characterization,

processing, assembly, and on-chip quality control.

Steven D. Hudson

The intricacy of biological systems inspires the

design of artificial systems that also function

through dynamic self-assembly and in-situ monitoring

and self-correction.

Our industrial partners identified measurement of

interfacial tension as a first hurdle for high-throughput

microfluidic fluids analysis. Particle processing and

assembly methods represent the next hurdle. In this

project, high-throughput tools are developed for

these purposes, and theoretical simulations identify

particle arrangements whose dynamic assembly and

disassembly is promising for sensor applications.

High-throughput measurement of drop shape

by image analysis represents the cornerstone of an

instrument, developed in collaboration with industrial

sponsors, that determines interfacial tension between

fluids. The measurement principle is simple and

robust — drops are stretched by known viscous

forces as they traverse a constriction in the channel.

The computer controlled system tracks drop position

and deformation more than one hundred times a second.

However, systems that count, isolate, and direct the

assembly of particles must operate more efficiently to

enable internal feedback mechanisms. Therefore, for

Nanometrology
18

Defects in Polymer Nanostructures

Nanostructured materials create new and unique

functionality through the accurate placement,

precise shaping, and chemical modification of

nanometer scale patterns. Such materials are to

be the basis of a wide range of emerging nanotechnologies that span optics, data storage, and

biomembranes. In each of these applications,

defects in pattern placement, shape, and chemical

composition can compromise device functionality.

The rapid development of these technologies

is currently offset by a lack of quantitative

characterizations of critical defects. We have

initiated this project to develop metrologies for

characterizing critical defects, such as loss of

long-range order, in nanostructured materials.

Ronald L. Jones and Alamgir Karim

The optical, magnetic, and electronic properties of

a film or surface are dramatically changed by the

inclusion and placement of nanometer-scale patterns.

The capability to adjust material properties in this

manner is central to the development of sub-wavelength

optics, high selectivity biomembranes, nanoparticle

synthesis, and ultrahigh capacity data storage. In each

of these applications, variations in pattern shape and

placement can drastically alter functionality and device

viability.

Fabrication of nanostructured surfaces is performed

through a wide range of patterning platforms. While

photolithographic techniques are traditional routes

toward precise patterning, the high cost and complexity

of patterning at nanometer length scales has spawned

a variety of alternative techniques such as nanoimprint

lithography (NIL), self-assembly, and templated

self-assembly. Each fabrication technique strives

against a common set of critical defects such as

variation in pattern placement, chemical uniformity

across the pattern cross section, and precision in

pattern shape.

To address the needs of this emerging technological

area, we have initiated a new program to develop

metrologies for long-range order, a critical parameter

in optical and data storage applications. Currently,

long-range order is quantified from Fourier transforms

of real-space microscopy images. However, the

disparity in the pattern length scale (~ 10 nm) and the

length scale of ordering (~ 100 μm) challenges the

measurement range of existing techniques based on

scanning electron and scanning probe microscopies.

Visible light probes are often complicated by complex

interactions with nanometer scale features.

Using small angle x-ray scattering (SAXS), we are

developing quantitative descriptions of long-range

order, grain size, and pattern shape in hexagonally

arrayed cylinders produced on silicon substrates using

both nanoimprint lithography (NIL) and self-assembled

block copolymers (BCP).

Figure 1: Scanning electron

microscopy image showing

a regular array of hexagonally

packed columns formed in

silicon oxide.

Figure 2: SAXS data from arrays of hexagonally packed

columns formed by NIL (left) and self assembly (right).

For each method of pattern formation, long-range

order results in a characteristic diffraction pattern.

However, the occurrence of a hexagonal diffraction pattern

from the NIL pattern indicates a single crystal spanning

the entire 150 x 150 μm beam spot, while the BCP film

consists of multiple, randomly oriented crystals. In both

cases, systematic errors in the placement of the patterns

on the lattice create a characteristic decay in the intensity

as a function of the distance from the beam center.

In addition to developing metrologies for long-range

order, we continue to develop a suite of metrologies that

address critical needs in a wide range of nanostructured

materials applications. These include nanostructured

surfaces for adhesion and wettability, as well as

nanostructured materials designed for unique

electro-optical and magnetic properties.

Contributors and Collaborators

J.F. Douglas (Polymers Division, NIST);

S. Satija (NIST Center for Neutron Research);

R. Briber (University of Maryland); H.-C. Kim (IBM)

Nanometrology
19

Critical Dimension Small Angle X-Ray Scattering

The feature size in microelectronic circuitry is

ever decreasing and now approaches the scale

of nanometers. This creates a need for new

metrologies capable of non-destructive

measurements of small features with sub-nm

precision. NIST has led the effort in developing

small angle x-ray scattering to address this need.

This x-ray based metrology has been included in

the ITRS roadmap as a potential metrological

solution for future generation microelectronics

fabrication. Other applications of this

technique in areas such as nano-rheology

and nanofabrication are being explored.

Wen-li Wu and Ronald L. Jones

The demand for increasing computer speed and

decreasing power consumption continues to shrink

the dimensions of individual circuitry components

toward the scale of nanometers. When the smallest,

or “critical”, dimensions are < 40 nm, the acceptable

tolerance will be < 1 nm. This creates significant

challenges for measurements based on electron

microscopy and light scatterometry. Device viability

also requires the measurement be non-destructive.

In addition, the continuing development of new materials

for extreme ultraviolet photoresists, nanoporous low-k

dielectrics, and metallic interconnects all require

high-precision dimensional measurements for process

development and optimization.

To address industrial needs, we are developing a

high-precision x-ray based metrology termed Critical

Dimension Small Angle X-ray Scattering (CD-SAXS).

This technique is capable of non-destructive

measurements of test patterns routinely used by

microelectronic industries to monitor their fabrication

process. A collimated monochromatic x-ray beam

of sub-Å wavelength is used to measure the pattern

dimensions on a substrate in transmission mode.

CD-SAXS has previously demonstrated a capability

for sub-nm precision for periodicity and line width

measurements.

This year, we have extended the capabilities to

provide more detailed quantifications of the pattern

cross section. This includes both basic dimensions,

such as pattern height and sidewall angle, as well as the

depth profile of the sidewall damage of nano-patterned

low-k dielectrics. The capability to provide basic

dimensions is complementary to existing analyses

provided by SEM, however CD-SAXS offers significant

advantages in its non-destructive capability. In contrast

to visible light scatterometry, detailed information on

refractive indices and composition of the pattern are not

required for data reduction. These capabilities and the

ability to measure patterns approaching dimensions of

10 nm have led to the inclusion of CD-SAXS on the

International Technology Roadmap for Semiconductors

(ITRS) as a potential metrology for the 45 nm

technology node and beyond.

So far, all CD-SAXS measurements have been

carried out at the Advanced Photon Source of

Argonne National Laboratory. As an important step

in demonstrating the potential of technology transfer,

we are constructing the world’s first laboratory

based CD-SAXS instrument. When completed, this

instrument will serve as a prototype for lab-based tool

development as well as a world-class metrology tool

for nanotechnology research.

Future efforts will develop capabilities for

quantifying defects and features with complex shapes

such as vias or contact holes. In addition, we will

continue to expand efforts in supporting other

nanofabrication technologies such as those based

on nanoimprint and self assembly.

Contributors and Collaborators

C. Soles, H. Lee, H. Ro, E. Lin (Polymers Division,

NIST); K. Choi (Intel); D. Casa, S. Weigand, D. Keane

(Argonne National Laboratory); Q. Lin (IBM)

Figure 1: Diffraction patterns collected over a range of sample

rotation angles. The distance between the pronounced horizontal

ridges provides the sidewall angles β, while the relative intensity

and placement of the other diffraction spots provide periodicity,

line width, and line height. [qx = 4 π sin(θ /2)/λ, where θ is the

angle relative to the diffraction axis and λ is the wavelength of

the radiation.]

Nanometrology
20

Nanoimprint Lithography

Nanoimprint lithography (NIL) is emerging as

a viable next generation lithography with high

throughput and a patterning resolution better than

10 nm. However, wide-spread availability of such

small nanoscale patterns introduces new metrology

challenges as the ability to pattern now surpasses

the capability to measure, quantify, or evaluate the

material properties in these nanoscale features.

We develop high-resolution metrologies to augment

and advance NIL technology, with current focus

on characterizing shape and the fidelity of

pattern transfer.

Christopher L. Soles and Ronald L. Jones

Nanoimprint lithography (NIL) is a conceptually

simple process whereby nanoscale patterns are

written once into a master, typically Si, quartz, or some

other hard material, using a high resolution but slow

patterning technology such as e-beam lithography.

This master can be rapidly and repeatedly replicated

by stamping it into a softer resist film. This imprint

replication technique is a cost-effective way to combine

the high-resolution patterning of e-beam lithography

with the high throughput of a stamping process.

cross-section (height, width, side-wall angle) with

nm resolution. Likewise, specular x-ray reflectivity

(SXR) was introduced to quantify the pattern

cross-section and the residual layer thickness with nm

resolution. In turn, these accurate shape metrologies

enable quantitative studies of imprint resolution and

the stability of nanoscale imprinted patterns.

Using CD-SAXS, we demonstrated the fidelity of

pattern transfer concept. The pattern cross-sections

in the master and the imprint were independently

characterized and then compared, to quantify how well

the resist material fills and replicates the features of

the master. Varying the imprint temperature, pressure,

time, and the molecular mass of the imprint material

impacts the fidelity of pattern transfer process. We

also tracked the in-situ evolution of the cross-section

while the patterns were annealed close to their glass

transition. Rather than a viscous decay, the patterns

decreased in height much faster than they broadened in

width, owing to the residual stresses in the structures

induced by the imprinting procedure. These residual

stresses appear to increase with molecular mass, leading

to faster rates of pattern decay in higher molecular mass

resists.

NIL holds great promise in semiconductor

fabrication. The high resolution and low cost of

ownership make NIL attractive in comparison to

expensive next-generation optical lithography tools.

However, over the past few years, the interest in NIL

has dramatically expanded beyond the realm of

traditional CMOS applications. NIL-based solutions

are being implemented for optical communications,

memory, displays, and biotechnology. Because of these

emerging niche applications, NIL is quickly becoming

a widely used and versatile nanofabrication tool.

Our objective is to develop metrologies that are

crucial to advancing NIL as an industrially viable

patterning technology. Initial efforts have focused on

developing and applying very accurate pattern-shape

measurements. Critical dimension small angle x-ray

scattering (CD-SAXS) is a transmission x-ray scattering

technique that can quantify the pattern pitch and

SXR was used to quantify the residual layer

thickness, pattern height, and the relative line shape

cross-section. The residual layer is the thin layer of

resist that the master is unable to fully displace as it is

pressed into the resist film. Precise knowledge of the

residual thickness is critical for subsequent etching

processes. The key to this measurement is that the

x-rays average density over length scales larger than

the sub-μm dimensions of the patterns. This leads to

the bilayer equivalency model shown above where the

patterns can be modeled as a uniform layer of reduced

density to extract pattern height and residual layer

thickness with nm precision. Like CD-SAXS, SXR

quantitatively compares the imprint and the mold to

evaluate the fidelity of pattern transfer.

Contributors and Collaborators

H.W. Ro, H.-J. Lee, A. Karim, E.K. Lin, J.F. Douglas,

W. Wu (Polymers Division, NIST); S.W. Pang

(University of Michigan); D.R. Hines (University of

Maryland); C.G. Willson (University of Texas–Austin);

L. Koecher (Nanonex); D. Resnick (Molecular

Imprints)

Nanometrology
21

Program Overview

Materials for Electronics

The U.S. electronics industry faces strong

international competition in the manufacture of smaller,

faster, more functional, and more reliable products.

Many critical challenges facing the industry require

the continual development of advanced materials

and processes. The NIST Materials Science and

Engineering Laboratory (MSEL) works closely with

U.S. industry, covering a broad spectrum of sectors

including semiconductor manufacturing, device

components, packaging, data storage, and assembly,

as well as complementary and emerging areas such as

optoelectronics and organic electronics. MSEL has a

multidivisional approach, committed to addressing the

most critical materials measurement and standards

issues for electronic materials. Our vision is to be

the key resource within the Federal Government for

materials metrology development and will be realized

through the following objectives:

■ Develop and deliver standard measurements and data

for thin film and nanoscale structures;

■ Develop advanced measurement methods needed by

industry to address new problems that arise with the

development of new materials;

■ Develop and apply in situ as well as real-time, factory

floor measurements for materials and devices having

micrometer to nanometer scale dimensions;

■ Develop combinatorial material methodologies for

the rapid optimization of industrially important

electronic and photonic materials;

■ Provide fundamental understanding of the divergence

of thin film and nanoscale material properties from

their bulk values;

■ Provide fundamental understanding, including first

principles modeling, of materials needed for future

nanoelectronic devices.

The NIST/MSEL program consists of projects led

by the Metallurgy, Polymers, Materials Reliability, and

Ceramics Divisions. These projects are conducted in

collaboration with partners from industrial consortia

(e.g., SEMATECH), individual companies, academia,

and other government agencies. The program is

strongly coupled with other microelectronics programs

within the government such as the National Semiconductor

Metrology Program (NSMP). Materials metrology

needs are also identified through the International

Technology Roadmap for Semiconductors (ITRS), the

International Packaging Consortium (IPC) Roadmap,

the IPC Lead-free Solder Roadmap, the National

Electronics Manufacturing Initiative (NEMI) Roadmap,

the Optoelectronics Industry Development Association

(OIDA) Roadmap, and the National Magnetic Data

Storage Industry Consortium (NSIC) Roadmap.

MSEL researchers from each division have made

substantial contributions to the most pressing technical

challenges facing industry, from new fabrication

methods and advanced materials in the semiconductor

industry, to low-cost organic electronics, and to novel

classes of electronic ceramics. Below are just a few

examples of MSEL contributions over the past year.

Advanced Gate Dielectrics

To enable further device scaling, the capacitive

equivalent thickness (CET) of the gate stack thickness

must be 0.5 nm to 1.0 nm. This is not achievable with

existing SiO2/polcrystalline Si gate stacks. High dielectric

constant gate insulators are needed to replace SiO2, and

metal gate electrodes are needed to replace polycrystalline

Si. Given the large number of possible materials choices

for the gate dielectric/substrate and gate dielectric/metal

gate electrode interfaces, the MSEL Ceramics Division

is establishing a dedicated combinatorial film deposition

facility to study the complex interfacial interactions.

This same methodology is applicable to a wide variety

of problems in the electronic materials field.

Advanced Lithography

Lithography is the key enabling technology for the

fabrication of advanced integrated circuits. As feature

sizes decrease to sub-65 nm length scales, challenges arise

because the image resolution and the thickness of the

imaging layer approach the dimensions of the polymers

used in the photoresist film. Unique high-spatial

resolution measurements are developed to identify the

limits of materials and processes for the development

of photoresists for next-generation lithography.

Advanced Metallization

As the dimensions of copper metallization

interconnects on microelectronic chips decrease below

100 nm, control of electrical resistivity becomes critical.

The MSEL Metallurgy Division is developing seedless

deposition methods that will simplify thin-film processing

and result in film growth modes that increase trench

filling, thus lowering interconnect resistivity.

Mechanical Reliability of Microchips

One of the important ITRS challenges is to achieve

effective control of the failure mechanisms affecting

chip reliability. Detection and characterization methods

for dimensionally constrained materials will be critical to

the attainment of this objective. Scientists in the MSEL

Materials Reliability Division are addressing this issue by

focusing on electrical methods capable of determining

the thermal fatigue lifetime and mechanical strength of

patterned metal film interconnects essential to microchips.

Contact: Eric K. Lin
22

Polymer Photoresists for 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 65 nm length

scale, 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 65 nm lithography.

Vivek M. Prabhu

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 manufacture of nanoscale structures.

In this process, a designed pattern is transferred to the

silicon substrate by altering the solubility of areas of

a polymer-based photoresist thin film through an

acid-catalyzed deprotection reaction after exposure

to radiation through a mask (Figure 1). To fabricate

smaller features, next-generation photolithography

will be processed with shorter wavelengths of light

requiring photoresist films less than 100 nm thick and

dimensional control to within 2 nm.

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 that can significantly affect the

patterning process at nanometer scales.

This year, we initiated two new collaborations.

With SEMATECH, we are determining the materials

sources of line-edge roughness in model 193-nm

photoresists. With the Intel Corporation, we are

investigating the effect of extreme ultraviolet (EUV)

exposure on pattern resolution of model EUV

photoresist materials. With these partners, we continue

to provide 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 scattering (SANS), near-edge x-ray

absorption fine structure (NEXAFS) spectroscopy,

combinatorial methods, solid state nuclear magnetic

Photoresists are multi-component mixtures that

require dispersion of additives, controlled transport

properties during the interface formation, and controlled

dissolution behavior. The fidelity of pattern formation

relies on the materials characteristics. We examine the

influence of copolymer compositions, molecular mass,

and photoacid generator additive size to determine

the root causes of image quality by highlighting

the fundamental polymer physics and chemistry.

In addition, our collaborators test our hypotheses

using 193-nm and EUV lithographic production tools.

Accomplishments for this past year include:

quantification of the developer profile in ultrathin films by

NR and QCM; quantification of the deprotection reaction

kinetics and photoacid-reaction diffusion deprotection

front for resolution and roughness fundamentals by

combined NR and FTIR; photoacid generator miscibility

and dispersion in complex photoresist co- and ter-polymers

by NMR; and aqueous immersion dependence on

photoresist component leeching by NEXAFS.

Contributors and Collaborators

B. Vogt, A. Rao, S. Kang, D. VanderHart, W. Wu,

E. Lin (Polymers Division, NIST); D. Fischer,

S. Sambasivan (Ceramics Division, NIST); S. Satija (NIST

Center for Neutron Research); K. Turnquest (Sematech);

K-W. Choi (Intel); D. Goldfarb (IBM T.J. Watson

Research Ctr); H. Ito, R. Allen (IBM Almaden Research

Ctr); R. Dammel, F. Houlihan (AZ Electronics);

J. Sounik, M. Sheehan (DuPont Elect. Polymers)

Figure 1: Key lithographic process steps; each step requires an

interdisciplinary array of experimental techniques to measure the

polymer chemistry and physics in thin films. A model 193-nm

resist under investigation is shown with the acid-catalyzed

deprotection reaction.

resonance (NMR)/spectroscopy, quartz crystal

microbalance (QCM), Fourier transform infrared

spectroscopy (FTIR), fluorescence correlation

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

Materials for Electronics
23

Organic Electronics

Organic electronics has dramatically emerged in

recent years as an increasingly important technology

encompassing a wide array of devices and

applications including embedded passive devices,

flexible displays, and sensors. Device performance,

stability, and function critically depend upon charge

transport and material interaction at the interfaces

of disparate materials. We develop and apply

nondestructive measurement methods to characterize

the electronic and interfacial structure of organic

electronics materials with respect to processing

methods, processing variables, and materials

characteristics.

Eric K. Lin and Dean M. DeLongchamp

Organic electronic devices are projected to

revolutionize new types of integrated circuits

through new applications that take advantage of low-cost,

high-volume manufacturing, nontraditional substrates,

and designed functionality. The current state of organic

electronics is slowed by the concurrent development

of multiple material platforms and processes and a lack

of measurement standardization between laboratories.

A critical need exists for new diagnostic probes, tools,

and methods to address these technological challenges.

Organic field effect transistor test structures were

also designed and fabricated onto silicon wafers with

variations in transistor channel length and width. Devices

constructed using organic semiconductors such as

poly(3-hexyl thiophene) (P3HT) were tested for their

electrical characteristics such as the field effect hole

mobility, on/off ratios, and threshold mobilities. Variations

in mobility, for example, are observed with changes in

processing variables such as annealing temperature and

casting solvent. Correlations are found between device

performance and the microstructure of P3HT as quantified

by NEXAFS, optical ellipsometry, and FTIR spectroscopy.

Contributors and Collaborators

J. Obrzut, B. Vogel, C. Chiang, K. Kano, C. Brooks,

N. Fisher, B. Vogt, H. Lee, Y. Jung, W. Wu (Polymers

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

Division, NIST); M. Gurau, L. Richter (Chemical

Science and Technology Laboratory, NIST); C. Richter,

O. Kirillov (Electronics and Electrical Engineering

Laboratory, NIST); R. Crosswell (Motorola);

L. Moro, N. Rutherford (Vitex); A. Murphy,

J.M.J. Frechet, P. Chang, V. Subramanian (University

of California–Berkeley); M. Ling, Z. Bao (Stanford

University); M. Chabinyc, Y. Wu, B. Ong (Xerox)

Figure 1: Schematic of the geometry of near-edge x-ray absorption

fine structure (NEXAFS) spectroscopy for the determination of

the orientation of an oligothiophene organic semiconductor

synthesized by the University of California–Berkeley.

Organic electronics presents different measurement

challenges from those identified for inorganic devices.

We are developing an integrated suite of metrologies to

correlate device performance with the structure, properties,

and chemistry of materials and interfaces. We apply

new measurement methods to provide the data and

insight needed for the rational and directed development

of emerging materials and processes. Studies include

AC measurements of organic semiconductor thin films,

Figure 2: Schematic of an organic field effect transistor (OFET)

and a photo of the NIST OFET test bed fabricated onto silicon.

the influence of surface modification layers on device

performance, and the evaluation of moisture barrier

layers for device encapsulation.

This year, near-edge x-ray absorption fine structure

(NEXAFS) spectroscopy was applied to several classes

of organic electronics materials to investigate the

electronic structure, chemistry, and orientation of

these molecules near a supporting substrate. NEXAFS

spectroscopy was used successfully to quantify the

simultaneous chemical conversion, molecular ordering,

and defect formation of soluble oligothiophene

precursor films for application in organic field effect

transistors. Variations in field-effect hole mobility

with thermal processing were directly correlated to

the orientation and distribution of molecules within

3 nm to 20 nm thick films.

Materials for Electronics
24

Nanoporous Low-k Dielectric Constant Thin Films

NIST provides the semiconductor industry with

unique on-wafer measurements of the physical

and structural properties of nanoporous thin films.

Several complementary experimental techniques are

used to measure the pore and matrix morphology of

candidate materials. The data are used by industry

to select candidate low-k materials. Measurement

methods such as x-ray porosimetry and small

angle x-ray scattering are developed that may be

transferred to industrial laboratories. Methods are

being developed to measure patterned low-k samples

and to assess the extent of structure modification

caused by plasma etch.

Eric K. Lin and Wen-li Wu

Future generations of integrated circuits will require

porous low-k interlayer dielectric materials to

address issues with power consumption, signal

propagation delays, and crosstalk that decrease device

performance. The introduction of nanometer scale

pores into a solid film lowers its effective dielectric

constant. However, increasing porosity adversely

affects other important quantities such as the physical

strength needed to survive chemical mechanical

polishing steps and barrier properties to contaminants

such as water. These effects pose severe challenges

to the integration of porous dielectrics into the

device structure.

There is a need for nondestructive, on-wafer

characterization of nanoporous thin films. Parameters

such as the pore size distribution, wall density, porosity,

film uniformity, elemental composition, coefficient

of thermal expansion, and film density are needed to

evaluate candidate low-k materials. NIST continues

to develop low-k characterization methods using a

combination of complementary measurement methods

including small angle neutron and x-ray scattering

(SANS, SAXS), high-resolution x-ray reflectivity (XR),

x-ray porosimetry (XRP), SANS porosimetry, and ion

scattering. To facilitate the transfer of measurement

expertise, a recommended practice guide for XRP is

available for interested researchers.

In collaboration with industrial and university

partners, we have applied existing methods to new

low-k materials and developed new methods to address

upcoming integration challenges. A materials database

developed in collaboration with SEMATECH is used

extensively by SEMATECH and its member companies

to help select candidate materials and to optimize

integration processing conditions. We address the

effects of the ashing/plasma etch process on the low-k

material during pattern transfer. Often surfaces

exposed to ashing/plasma densify and lose terminal

groups (hydrogen or organic moiety) resulting in an

increased moisture adsorption and thus dielectric

constant. XR measurements enable quantification

of the surface densification or pore collapse in

ashing-treated and/or plasma-treated blanket films.

Figure 1: Four models of the damage layer profile plotted as

scattering length density (SLD) as a function of position within a

line. The matrix has a relative SLD of zero in the above plots.

This year, a new method using SAXS was

developed to investigate the effect of plasma etch on

patterned low-k films. After the plasma etch process,

samples are backfilled with the initial low-k material.

Any densification of the sidewall may be observable by

x-ray scattering from the cross-section of a patterned

nanostructure. This SAXS work was carried out at

Argonne National Laboratory using line gratings of

low-k material. The resulting data can then be

compared with several different scattering models

for the densification of the patterned low-k material

as shown in Figure 1. Distinctions between models

such as these will significantly help semiconductor

manufacturers to accelerate the integration of low-k

materials into next generation devices.

Contributors and Collaborators

H. Lee, C. Soles, R. Jones, H. Ro, D. Liu, B. Vogt

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

for Neutron Research); Y. Liu (SEMATECH); Q. Lin,

A. Grill, H. Kim (IBM); J. Quintana, D. Casa (Argonne

National Laboratory); K. Char, D. Yoon (Seoul National

University); J. Watkins (University of Massachusetts)

Materials for Electronics
25

Program Overview

Advanced Manufacturing Processes

The competitiveness of U.S. manufacturers depends

substantially on their ability to create new product concepts

and to quickly translate such concepts into manufactured

products that meet their customers’ increasing expectations

of performance, cost, and reliability. This is equally true

for well-established “commodity” industries, such as

automotive, aerospace, and electronics; for materials

suppliers of aluminum, steel, and polymers; and for

rapidly growing industries based on nanotechnology

and biotechnology. In support of these industries,

MSEL is developing robust measurement methods,

standards, software, and process and materials data

needed for design, monitoring, and control of new

and existing materials and their manufacturing processes.

The Advanced Manufacturing Processes Program focuses

on the following high-impact areas:

■ Development of combinatorial and high-throughput

methods for developing and characterizing materials

ranging from thin films and nanocomposites to micro

and macroscale materials structures;

■ Automotive industry-targeted R&D for improved

measurement methods for sheet metal forming

of lightweight metals and for the development

of hydrogen storage materials needed for

hydrogen-powered vehicles;

■ Development of innovative, physics-based process

modeling tools for simulating phase transformations

and deformation during manufacturing and creation

of the databases that support such simulations;

■ National traceable standards having a major impact

on trade, such as hardness standards for metals and

MALDI process standards for polymers; and

■ Development of innovative microfluidic testbeds

for process design and characterization of polymer

formulations.

Our research is conducted in close collaboration

with industrial partners, including industrial consortia,

and with national standards organizations. These

collaborations not only ensure the relevance of our

research, but also promote rapid transfer and utilization

of our research by our partners. Three projects from the

Advanced Manufacturing Methods Program are

highlighted below.

NIST Combinatorial Methods Center (NCMC)

The NCMC develops innovative combinatorial and

high-throughput (C&HT) measurement techniques and

experimental strategies for accelerating the discovery

and optimization of complex materials and products,

such as polymer coatings and films, structural plastics,

fuels, personal care goods, and adhesives. These

C&HT array and gradient methods enable the rapid

acquisition and analysis of physical and chemical

data from materials libraries, thereby accelerating

materials discovery, manufacturing design, and

knowledge generation. In 2005, the NCMC

Consortium consisted of 19 institutions from industry,

government laboratories, and academic groups, which

represents a broad cross-section of the chemical and

materials research sectors. A growing component of

the NIST NCMC program is focused on accelerating

the development and understanding of emerging

technologies, including nanostructured materials,

organic electronics, and biomaterials, and, in particular,

on the nanometrology needed for C&HT-based

research for these technologies.

Forming of Lightweight Materials

Automotive manufacturing is a materials intensive

industry that involves approximately 10 % of the U.S.

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

cost-effective technologies, this globally competitive

industry has major productivity issues related to

materials measurements, materials modeling, and

process design. Chief among these is the difficulty

of designing stamping dies for sheet metal forming.

An ATP-sponsored workshop (“The Road Ahead,”

June 20–22, 2000) identified problems in the production

of working die sets as the main obstacle to reducing

the time between accepting a new design and actual

production of parts. This is also the largest single

cost (besides labor) in car production. Existing finite

element models of deformation and the materials

measurements and data on which they are based are

inadequate to the task of evaluating a die set design:

they do not accurately predict the multi-axial hardening,

springback, and friction of sheet metal during metal

forming processes and, therefore, the stamping dies

designed using finite element analyses must be modified

through physical prototyping to produce the desired

shapes, particularly for high-strength steels and

aluminum alloys. To realize the weight savings and

increased fuel economy enabled by high-strength

steel and aluminum alloys, a whole new level of

formability measurement methods, models, and data

is needed for accurate die design, backed by a better

understanding of the physics behind metal deformation.

The MSEL Metallurgy Division is working with the

U.S. automakers and their suppliers to fill these needs.

A key component of our program is the unique

multi-axial deformation measurement facility with

which local strains in deformed metal sheet can be

measured in situ. This facility has enabled NIST

to take a key role in developing new methods for
26

assessing springback, residual stresses, friction

between the sheet metal and die during forming, and

surface roughening, and in providing benchmark data

for international round-robin experiments for finite

element code. New techniques for detecting local

deformation events at surfaces are providing insights

into the physics of deformation and are leading to

physics-based constitutive equations.

Hardness Standardization:

Rockwell, Vickers, and Knoop

Hardness is the primary test measurement used to

determine and specify the mechanical properties of

metal products and, as such, determines compliance

with customer specifications in the national and

international marketplace. The MSEL Metallurgy

Division is engaged in developing and maintaining

national traceability for hardness measurements and

in assisting U.S. industry in making measurements

compatible with other countries around the world,

enabled through our chairing the ASTM International

Committee on Indentation Hardness Testing and heading

the U.S. delegation to the ISO Committee on Hardness

Testing of Metals, which oversees the development

of the organizations’ respective hardness programs.

Our specific R&D responsibilities include the

standardization of the national hardness scales,

development of primary reference transfer standards,

leadership in national and international standards

writing organizations, and interactions and comparisons

with U.S. laboratories and the National Metrology

Institutes of other countries.

Contact: Michael J. Fasolka

Program Overview
27

NIST Combinatorial Methods Center

Pioneer and Partner in Accelerated Materials Research

Combinatorial and high-throughput (C&HT)

methods hold great potential for making materials

research more productive, more thorough, and less

wasteful. However, significant barriers prevent

the widespread adoption of these revolutionary

techniques. Through creative, cost-effective

measurement solutions, and with an eye towards

fruitful collaboration, the NIST Combinatorial

Methods Center (NCMC) strives to ease the

acquisition of C&HT techniques by the materials

research community.

Michael J. Fasolka

The NIST Combinatorial Methods Center is now in

its fourth year of service to industry, government

laboratories, and academic groups interested in acquiring

C&HT capabilities for materials research. In 2005, the

NCMC consortium included 19 member institutions

(see table), which represent a broad cross-section of the

chemical and materials research sectors.

The NCMC fosters wide-spread adaptation of

C&HT technologies through two complementary efforts.

The first is an extensive research program, centered in

the Multivariant Measurement Methods Group of the NIST

Polymers Division. Our research provides innovative

measurement solutions that serve to accelerate the

discovery and optimization of complex products such

as polymer coatings and films, structural plastics, fuels,

personal care goods and adhesives. Moreover, a growing

component of our program aims to speed the development

and understanding of emerging technologies including

nanostructured materials, nanometrology, organic

electronics, and biomaterials. Several of these research

directions are highlighted elsewhere in this report,

as identified by the NCMC symbol (see top right).

emerging industrial needs for C&HT measurements

of materials systems such as biomaterials and organic

electronics. Accordingly, NCMC-6 included plenary

symposia outlining engineering issues in these advanced

systems, sessions illustrating NIST capabilities in these

areas, and a panel discussion aimed at determining new

measurements that should be pursued.

In addition, on May 2–3 2005, we hosted NCMC-7:

Adhesion and Mechanical Properties II. Central to

this event was a symposium presenting new NCMC

methods for the development and optimization of

adhesives. Highlights included a new gradient peel-test

for the HT assessment of backed adhesives (e.g., tapes),

and approaches for the rapid screening of epoxy

formulations. A variation of our buckling technique to

measure modulus, useful for evaluating soft systems

such as polymer gels, was also described.

Advanced Manufacturing Processes

“As a member of NCMC, I believe that Procter & Gamble has

access to a high-performance work group with expertise in high

throughput and combinatorial techniques. The conferences

have been particularly valuable for networking with NIST

scientists as well as other industrial members of NCMC.”

— M. McDonald (Procter and Gamble)

“The coatings industry has been traditionally perceived to react

slowly to implementing newer and quantifiable measurement

techniques for characterizing structure–property relationships

in paints and films. The [NCMC] has pioneered elegant

approaches that can significantly reduce experimental time

[for] testing coating formulation performance.”

— D. Bhattacharya (Eastman Chemical)

In conjunction with its research program, the

NCMC conducts an outreach effort to disseminate

NIST-developed C&HT methods, assess industry

measurement needs, and form a community to advance

the field. A key component of NCMC outreach is our

series of member workshops. On November 8–9 2004,

we hosted our 6th workshop, NCMC-6: Advanced

Materials Forum. The goal of NCMC-6 was to gauge

“The combinatorial methods program at NIST makes the NCMC

critical to any company’s development of high-throughput

workflows. The import of this effort to industry is clearly

indicated by your center’s number of industrial members.”

— J. Dias (ExxonMobil)

Moreover, this year the NCMC continued community

forming activities by organizing several high-profile

sessions dedicated to C&HT research at national

conferences, including meetings of the American Physical

Society, the American Chemical Society, the Materials

Research Society, and the Adhesion Society.

Contributors and Collaborators

C.M. Stafford, P.M. McGuiggan, K.L. Beers,

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

NCMC Members (*New in FY2005):

Hysitron International

Intel

ICI/National Starch & Chemicals 

L’Oreal*

PPG Industries

Procter & Gamble

Rhodia

Univ. of Southern Mississippi

Veeco/Digital Instruments

Air Force Research Lab

Air Products & Chemicals 

Arkema Inc.

BASF

Bayer Polymers

BP

Dow Chemical Company

Eastman Chemical

ExxonMobil Research

Honeywell International

For more information on the NIST Combinatorial

Methods Center, please visit http://www.nist.gov/combi.
28

Polymer Formulations:

Materials Processing and Characterization on a Chip

We develop high-throughput methods to

advance polymer formulations science through

the fabrication of microscale instrumentation

for measuring physical properties of complex

mixtures. Adaptation of microfluidic technology

to polymer fluid processing and measurements

provides an inexpensive, versatile alternative

to the existing paradigm of combinatorial

methods. We have built a platform of polymer

formulations-related functions based on

modified microfluidic device fabrication

methods established in our facilities.

Kathryn L. Beers

Microfluidic device fabrication methods previously

developed in the Polymers Division enable

combinatorial fabrication and characterization of

polymer libraries. Recent accomplishments include

the integration of multiple functions on a chip for the

formulation, mixing, processing, and characterization

of polymer particles for evaluation of dental composite

materials and the fabrication of gradient polymer

brush surfaces for measuring the behavior of

stimuli-responsive surfaces.

with shrinkage. The first publication on this work

(Langmuir 21, 3629, 2005) was recently profiled in

the Research Highlights of Lab on a Chip.

Advanced Manufacturing Processes

Figure 1: (a) A thiolene microfluidic device used to create,

mix, polymerize and characterize monomer droplets.

(b) Optical images of monomer droplets and polymer particles.

(c) Raman spectra of monomer (red) and polymer (black).

Figure 2: (a) Schematic of amphiphilic block copolymer brush

gradients representing the proposed conformation shift in response

to good and poor solvents for the top block layer. (b) Water contact

angle measurements as a function of top block thickness on three

gradients of top block thickness on uniform bottom blocks of three

different lengths (blue – 4 nm, red – 10 nm, green – 14 nm) in good

(open) and poor (filled) solvents for the top block.

Building on our ability to form organic-phase

droplets in thiolene-based microfluidic devices

(Figure 1a), we can establish libraries of droplets

with systematic composition variations. The droplets

are subject to various processes such as mixing and

photopolymerization on the chip. Raman spectroscopy

on the chip (Figure 1c) and optical imaging (Figure 1b)

are used to measure and correlate properties such as

monomer composition and conversion to polymer

Microchannel confined surface initiated polymerization

was used to prepare surfaces with gradients of molecular

mass and block and statistical copolymer composition.

The block copolymer surfaces were studied for their ability

to reorganize at the air/solution interface depending

on the nature of the polymer and solvent (Figure 2a).

The ability of the surface layer to rearrange was shown

to depend on the thickness of both the top and bottom

block layers (Figure 2b).

The capabilities for controlled radical polymerization

on a chip (CRP Chip) were also extended this year to

include block copolymer synthesis and higher-order

control of solution compositions. A three-input device

was developed, enabling stoichiometric variations in

reactions and faster measurement of kinetic behavior

(Macromol. Rapid Commun. 26, 1037, 2005).

Contributors and Collaborators

Z.T. Cygan, C. Xu, S. Barnes, T. Wu, A.J. Bur,

J.T. Cabral, S.D. Hudson, A.I. Norman, J. Pathak,

W. Zhang, M.J. Fasolka, E.J. Amis (Polymers Division,

NIST)
29

Matrix-assisted laser desorption ionization

time-of-flight mass spectrometry (MALDI-TOF-MS)

is being developed as a method for absolute

molecular mass distribution measurement of

synthetic polymers. This means determining a

comprehensive uncertainty budget for a complex

measurement technique that must include both

Type A (“random”) and Type B (“systematic”)

uncertainties.

William E. Wallace

I

n mass spectrometry, methods exist to calibrate

 the mass axis with high precision and accuracy.

In contrast, the ion-intensity axis is extremely difficult

to calibrate. This leads to large uncertainties in

quantifying the content of mixtures. This is even true

when the mixture is composed solely of different mass

oligomers of the same chemical species as in the case

of polymer polydispersity. The aim of this project is

to calibrate the ion intensity axis. This task has

been divided into three parts: sample preparation/ion

production, instrument optimization/ion separation,

and data analysis/peak integration. Each part is

necessary but on its own is not sufficient to

guarantee quantitation.

We study the MALDI ion-creation process

phenomenologically using combinatorial libraries.

The ratio of analyte to matrix is varied along a linear

path laid down by nebulizing a continuously varying

mixture of two solutions, one analyte+matrix+ salt

and the other matrix+salt. In our case, the analyte is

a mixture of two polymers having different end groups

and closely matched molecular mass distributions.

The figure on this page shows such a library

where the blue arrows indicate a linearly changing

analyte:matrix ratio.

To this, we add stochastic-gradient numerical

optimization to adjust the instrument parameters at

each composition to give a mass spectrum that best

matches the known polymerA:polymerB ratio in the

analyte. Instrument parameters optimized include

laser energy, ion extraction voltage, ion lens

voltage, extraction delay time, and detector voltage.

Stochastic methods must be used because the data

have some measure of Type A random uncertainty

(i.e., “noise”) to them; therefore, exact values of the

function to be optimized are not available.

Finally, to this we add our MassSpectator software

which ensures unbiased, logically-consistent integration

of the peaks in the (noisy) mass spectrum. A software

script has been written around MassSpectator that

automatically identifies oligomeric series in the mass

spectrum and calculates the total amount and the

molecular mass moments for each series identified.

Advanced Manufacturing Processes

Quantitative Polymer Mass Spectrometry

An early embodiment of our approach can be

found in ASTM Standard Test Method D7134, the

first MALDI-TOF-MS method endorsed by ASTM.

Working through the Versailles Project on Advanced

Materials and Standards (VAMAS), and in close

cooperation with our industry and national metrology

institute (NMI) colleagues from around the world, an

interlaboratory comparison was initiated to understand

the nexus of critical measurement factors when

performing quantitative polymer mass spectrometry.

From the knowledge gained by the interlaboratory

comparison, D7134 was written with particular

attention paid toward controlling the critical factors.

The MALDI project maintains a vigorous,

worldwide outreach program including an online

polymer MALDI recipes catalog, annual polymer MS

workshops, and the availability of our MassSpectator

software on the web. For more information on

any of these topics please visit our web page at:

www.nist.gov/maldi.

Contributors and Collaborators

W.R. Blair, K.M. Flynn, C.M. Guttman (Polymers

Division, NIST); A.J. Kearsley (Mathematical &

Computational Sciences Division, NIST)
30
31

Biomaterials

Rapid development of medical technologies

depends on the availability of adequate methods to

characterize, standardize, control, and mass produce

them. To realize this goal, a measurement infrastructure

is needed to bridge the gap between the exponentially

increasing basic biomedical knowledge and clinical

applications. The MSEL Biomaterials Program is a

collaborative effort creating a new generation of

performance standards and predictive tools targeting

the metrology chain for biomedical research.

Today, all areas of materials science confront real

systems and processes. In the biomaterials arena,

we can no longer advance science by simply studying

ideal model systems. We must comprehend complex

realistic systems in terms of their structure, function,

and dynamics over the size range from nanometers to

millimeters. MSEL is uniquely positioned to make a

major contribution to the development of measurement

infrastructure through three focus areas: Systems

Biology, Bioimaging, and Nanobiosensing.

Systems Biology

MSEL research in systems biology focuses on

quantifying relationships of systems at the cell, tissue,

and organ level. To meet this need, we are developing

libraries of reference materials, high-throughput

techniques for screening libraries, and informatics

approaches for data analysis and interpretation.

Physicochemical and biochemical components are

organized using patterning, phase separating, and

self-assembling processes. Physicochemical

components of interest include modulus and surface

topography; biochemical components of interest

include peptide moieties that interact specifically

with cell receptors.

Gradient libraries of tyrosine derivatized

polycarbonate blends and fibronectin/poly(hydroethylmethacrylate) gradients were developed as reference

materials for biomaterial research, such that cell

responses included changes in geometry, distribution,

and proliferation, to assess intercellular communication

among osteoblast and fibroblast cells. Complementing

these surface studies, we are developing metrologies

to establish the relationship between 3D scaffold

morphology (i.e., porosity and permeability) and

cell response. Studies focused on identifying the

relationship between applied macroscopic stresses

and local stresses at the cellular level is also underway,

which will provide valuable input into development

of finite-element models.

Experiments on the mechanical stimulation

of tissues and tissue engineered constructs were

conducted to understand the role of metrology

in diagnostic testing of healthy or disease states.

Stress–strain relationships were defined for vascular

smooth muscle cells and bovine cardiac tissues.

Specialized bioreactors coupled to ultrasound and

infra-red spectroscopy were successful in differentiating

response among the systems. We have demonstrated

that the structure–property relations in healthy tissue

of pulmonary arteries, and in tissue that has remodeled

in response to the onset of disease, can be assessed

using mechanical testing, quantitative ultrasonic

characterization, and histology.

Bioimaging

Advances were made in developing and optimizing

physical methods and informatics tools to enhance

bioimaging and visualization technologies at multiple

length scales. With the reduction of background

noise, images were obtained using broadband coherent

anti-stokes Raman scattering microscopy with a 10-fold

increase in signal, and proteins on the surface of polymer

blends were differentiated. Optical techniques like OCM

and CFM, with spatial resolutions of ≈1 μm, were

employed to image dynamic cell culture experiments

in-situ in a bioreactor. Other advances in computational

modeling of single cell forces and cell populations were

carried out to predict normal ossification patterns and

cartilage formation. By combining information from

different techniques on the same sample and visualizing

structure using interactive, immersive visualization

techniques, scientists will gain new insights into the

physics and materials science of complex systems.

Nanobiosensing

Research in this focus area concentrates on the

development of techniques to measure and manipulate

biological atoms, molecules, and macromolecules at

the nanoscale level (1–100 nm). Mechanical tools

including an optical trap and bioMEMS devices that

can be integrated with currently used biological

techniques for evaluating and measuring cellular

response (i.e., gene expression, cell morphology,

area of adhesion) were developed. Additional studies

focus on identifying mechanical forces that indicate

the onset of osteogenesis and angiogenesis.

Contact: Eric J. Amis

Program Overview
32

Combinatorial Methods for Rapid Characterization

of Cell-Surface Interactions

The increasingly complex nature of functional

biomaterials demands a multidisciplinary

approach to identify and develop strategies

to both characterize and control cell-material

interactions. A robust framework outlining the

interactions governing biomaterial performance

does not exist but is desperately needed. This

project provides the basis for this framework

by focusing on fabrication of single and

multi-variable continuous combinatorial libraries

to rapidly identify compositions and physical

properties exhibiting favorable cell-material

interactions.

Matthew L. Becker and Lori A. Henderson

Developmental biology and tissue engineering are

avenues of research that must be fully integrated

to realize the opportunities in regenerative medicine.

For example, while the interactions between cell and

extracellular matrix have been studied extensively, much

less is understood regarding the influence of synthetic

materials. There is little doubt that having good control of

surface morphology as well as advanced high-throughput

(HT) metrologies for analyzing cell-surface interactions

are needed for biological interpretations, and while

chemical and topographical manipulations of surfaces

have been established, HT methods to evaluate

biological responses to these manipulations have not.

For these reasons, we are developing metrologies and

HT platforms to rapidly analyze physicochemical,

mechanical, and material properties of biomaterials.

We provide examples of two of our sample fabrication

methods, distinct from traditional self-assembled

monolayer approaches, that are being used to design,

manipulate, and quantify cell-surface interactions.

Two functional polymer surfaces, phase separated

tyrosine-derived polycarbonate blends (DTR-PC) and

conformational-based poly(2-hydroxyethyl methacrylate)

brushes [poly(HEMA)], were analyzed using combinatorial

methodologies. The DTR-PC films, consisting of

homopolymer and discrete composition blends of

tyrosine-derived polycarbonates, were shown to have

compositionally dependent gene expression profiles with

the blends differing significantly from the respective

homopolymers. Figure 1 illustrates the effect that polymer

blending has on cell spreading; the extension and distortion

of the lamellapodia increase and the cells appear to spread

less in the blend samples with increasing DTO content.

The surface properties from these discrete films will be

used to establish correlations and limitations for comparing

measurements from discrete samples and single and

multi-variable continuous gradient substrates.

Figure 1: AFM micrographs of the tyrosine-derived polycarbonate

homopolymers and discrete blends show compositionally dependent

phase separation, which is reflected in the immuno-fluorescent

staining for actin (red, cell spreading) and vinculin (green, focal

adhesion contacts) on MC3T3-E1 osteoblasts.

Figure 2: Schematic representation of the poly(HEMA)-FN

gradient and Fibroblast cell distribution.

Poly(HEMA) gradients were prepared to study

molecular interactions and cell conformation on

fibronectin (FN) coated poly(HEMA) by combining

“controlled” free radical polymerization with gradient

preparation technology. This gradient covers

“mushroom” to “brush” regimes in order to determine

how grafting density influences protein adsorption and

cellular response as shown in Figure 2. The number

of cells, their shape, and size were thus correlated to

the density of fibronectin across the gradient.

In summary, the tools developed in this program

will enable the design of material libraries to be used

to probe the behaviors of cells.

Contributors and Collaborators

N.D. Gallant, L.O. Bailey, C. Simon, Jr., T.W. Kee,

Y. Mei, J.S. Stephens, E.J. Amis (Polymers Division,

NIST); K. Langenbach, J.T. Elliot (Biotechnology

Division, NIST); J. Kohn, A. Rege, J. Schutt (Rutgers

University & The New Jersey Center for Biomaterials)

Biomaterials
33

Biomaterials

Cell Response to Tissue Scaffold Morphology

Industrial and regulatory sectors have expressed

a need for standards and new metrologies relating

to properties of tissue scaffolds for regenerative

medicine. We seek to meet these needs in several

areas where the criteria are clear, and to help

clarify industrial and regulatory needs in other

areas where such clarification is required. We are

developing a reference scaffold for porosity and

permeability. Also, we are developing metrologies

for establishing the relationship between scaffold

porosity/morphology and cell response, for

assessing the ability of a tissue scaffold to safely

host cytokine, and for quantifying mechanical

stimulation requirements for cells — at the cellular

level — from macroscopic inputs.

Marcus T. Cicerone

I

n the field of regenerative medicine, one seeks to

 guide cell differentiation and proliferation, and

production of the extracellular matrix through functional

properties of 3D tissue scaffolds. Developing the ability

to guide such cell behaviors requires first the ability to

characterize and assess properties of tissue scaffolds

as they relate to cell response. This, in turn, requires

well-defined physical and biological systems for which

quantitative rules can be formulated and verified.

We are developing methods for quantitatively

characterizing tissue scaffolds and the cellular

responses they elicit. There are three classes of

scaffold properties that we focus on relative to their

impact on cell behavior; these are: (i) morphological/

topological properties, (ii) mechanical properties, and

(iii) ability of biodegradable scaffold materials to act

as biopreservants in connection with hosting growth

factors and other cytokines.

We led a worldwide collaboration under ASTM with

17 other laboratories to establish a series of reference

scaffolds for porosity and permeability. Our primary

characterization method for these scaffolds is based on

tomographic image analysis of scaffold morphology.

We are developing metrologies for assessing osteoblast

response to pore size distributions in tissue scaffolds based

on extracellular matrix (ECM) production. We are also

investigating morphology effects on osteoblast response

to surface chemistry. The image analysis methods

developed in the reference scaffold activity serve to

support these efforts. The ability to uniformly and

reproducibly seed 3D scaffolds with adherent cells is

another critical factor for quantifying links between

scaffold morphology and cell response, and we have

developed methods to accomplish this.

We are using computational modeling coupled with

high-resolution imaging, atomic force microscopy

(AFM), and optical trapping to develop metrology in

the area of cell response to environmental mechanical

stresses. It is clear that mechanical stimulation is

required for some cell types to differentiate properly.

Thus, it is important to be able to measure precisely

what stress conditions are necessary for proper

phenotypic expression for selected cell types. We are

collaborating with the Materials Reliability Division

of MSEL to establish methods to quantify the stress

conditions at the cellular level based on macroscopic

forces placed on the scaffold construct. Our approach

is to translate ranges of macroscopic stresses to local

stresses experienced by cells using a finite element

model. These local stresses will be correlated with

cell response in terms of ECM production.

Biopreservation of cytokines in tissue scaffolds is a

complex but important area of regenerative medicine that

has been historically underserved. We are collaborating

with six academic and one national lab to create a holistic

approach to stabilizing proteins in solid hosts such as tissue

scaffolds. We are leading the grant-writing efforts in this

collaboration and are focusing on clarifying the relationship

between fast glassy dynamics and biopreserving ability

of a material, which we have already observed in neutron

scattering experiments. In keeping with this goal, we are

establishing accessible time-resolved optical metrologies

for measuring these dynamics.

Contributors and Collaborators

J. Dunkers, F. Wang, J. Cooper, T. DuttaRoy,

J. Stephens, F. Phelan, M.Y.M. Chiang, L. Henderson

(Polymers Division, NIST); Tim Quinn (Materials

Reliability Division, NIST)

Figure 1: A reconstruction of a candidate reference scaffold,

generated from a tomographic image. Each colored object

represents a separate unit cell within the pore structure of the scaffold.
34

3-Dimensional In Situ Imaging for Tissue Engineering:

Exploring Cell/Scaffold Interaction in Real Time

Real time investigations of cell/scaffold

interactions provide valuable information about

the dynamic nature of cells and their spatial

arrangements with respect to the three-dimensional

(3D) architecture of tissue engineering scaffolds.

In situ imaging capabilities will enable determination

of the structure/function relationship of tissue

engineering scaffolds and definition of the

necessary properties to promote tissue

regeneration. We demonstrate tools for

in situ imaging of cells/scaffold interactions.

Jean S. Stephens and Joy P. Dunkers

The ability to image live cells and their corresponding

interactions with the surrounding environment

provides critical information about the ability to promote

desired cellular activity (proliferation, differentiation,

etc.) for tissue regeneration. In order to develop

in situ optical imaging capabilities, we must be able

to nondestructively and noninvasively image the

interactions at the cell/scaffold interface while

maintaining cell viability.

In our laboratory, collinear optical coherent

microscopy/confocal fluorescence microscopy

(OCM/CFM) has successfully been used to image

the 3D interconnected porous structure of polymeric

scaffolds. This system combines high spatial resolution

(~1 μm), high sensitivity (>100 dB), and exceptional

depth-of-penetration associated with OCM with the

fluorescent capabilities of CFM. This, therefore, allows

us to not only investigate the 3D scaffold, but also the

use of conventional fluorescent staining techniques to

evaluate cellular response.

In order to perform live cell imaging, a system

or bioreactor that can sustain cell viability outside of

an incubator and allow for imaging was constructed

(Figure 1). The bioreactor is a perfusion flow

bioreactor. This design forces the media to flow

through the scaffold, therefore ensuring nutrient

delivery and oxygen perfusion, as well as waste

removal, throughout the entire structure. Also, a

dynamic cell culture creates an environment that better

mimics physiological conditions. The temperature

of the bioreactor system is maintained by circulating

water (37 °C) through a copper element.

Figure 1: Bioreactor in OCM/CFM, open and top view.

Figure 2: Time-lapse images of cell movement.

Initial in situ imaging studies indicate the

maintenance of cell viability, and we have successfully

imaged cells for several hours. The series of images

in Figure 2 illustrate cell movement over a 2 hour time

period. The ability to collect images in real time will

give a great insight and understanding of how cells

are responding to different materials, scaffold

architectures, and culture conditions. These data

will provide new metrics for the evaluation of

tissue engineering scaffolds.

Contributors and Collaborators

J.A. Cooper, C.R. Snyder (Polymers Division,

NIST)

Biomaterials
35

Broadband CARS Microscopy for Cellular/Tissue Imaging

In many of the biological sciences, as well as

many areas of polymer science, there is a need

for high-resolution, noninvasive, and chemically

sensitive imaging. We have developed a broadband

coherent anti-Stokes Raman scattering (CARS)

microscopy that provides an unprecedented

combination of imaging speed and spectral coverage

(i.e., chemical sensitivity). Our current efforts are

focused on eliminating nonresonant background

effects, which can limit sensitivity of the technique.

Marcus T. Cicerone

We have developed a broadband CARS microscopy

method which allows us to obtain vibrational

spectra in the range (500 to 3000) cm–1 in less than

1/50th the time required to obtain similar spectra by

spontaneous Raman. This development was reported

at the first meeting of National Institute for Biomedical

Imaging and Bioengineering (NIBIB) grantees, in

Bethesda, Maryland, the 11th Annual Time Resolved

Vibrational Spectroscopy Conference, and the

2005 Biophysical Meeting.

One key to the method we have developed is the

generation of a broadband continuum. Optical pumping

of a tapered silica fiber was used to generate broadband

continuum in the first prototype of this instrument.

Accumulative photo-damage limits the lifetime of the

tapered fiber, and seriously limits the power level of

the light that can be generated, significantly restricting

the taper fiber as a reliable light source for CARS

microscopy. With the assistance of an outside vendor,

we have designed and procured a photonic crystal

fiber (PCF) that is sealed at the ends, and which avoids

the above issues. The PCF did not show any sign of

degradation after a month, under long-term irradiation

of 40 kW peak power femtosecond laser pulses. This

advance provided ≈10-fold increase in signal levels,

so that, in principle, we can gather broadband spectra

in 1/500th the time required for spontaneous Raman

spectroscopy. In practice, this rate exceeds the

capabilities of the CCD camera, which therefore sets

the limits on data acquisition; a faster camera would

allow higher data collection rates.

A blend of chemically similar biodegradable

polymers, abbreviated as DTE and DTO (see Figure

1a), have induced remarkable low immune response

upon fibroblast cell adhesion. These two polymers

phase-separate upon annealing, and since they have

similar indices of refraction, optical microscopy cannot

be used to image the phase-separated domains. On the

other hand, broadband CARS microscopy has the

sensitivity to distinguish the two polymers. Figure 1

shows the three-dimensional imaging of a 50/50

DTE/DTO blend sample. In this sample, the spatial

resolution is approximately 0.4 μm. We are currently

exploring the hypothesis that the low cellular immune

response to the blends has its origins in spatial

patterning of the adhesion proteins. We are working

to correlate the protein adsorption with spatial

patterning of DTO and DTE rich domains.

In Figure 2, bright circular features are triglyceride

lipid droplets in adipocytes, and the more subdued

quasi-circular objects are the cells. We were unable

to image the presence of protein in the cytosol due to

nonresonant background. Detection of these proteins

is crucial to identifying cell type, and we are currently

focusing our efforts on substantially reducing the

effects of nonresonant background.

Contributors and Collaborators

T.W. Kee, H. Zhao, J. Taboas (Polymers Division,

NIST); W-J. Li, R. Tuan (NIH/NIAMS)

Figure 2: Micrograph of adipocyte. This image was obtained without

the use of contrast agents such as fluorescent stains; the 2845 cm–1

C-H stretch vibrational band was the only image contrast.

Figure 1: (a) Chemical structures of DTE and DTO. CARS

images of a 50/50 DTE/DTO blend at depth: (b) 0 μm, (c) 3 μm,

(d) 6 μm. The white areas in these images are DTO; the black

regions are DTE.

Biomaterials
36

Biomaterials

Molecular Design and Combinatorial Characterization

of Polymeric Dental Materials

Polymeric dental materials are finding increasing

applications in dentistry and allied biomedical

fields. As part of a joint research effort supported

by the National Institute of Dental and Craniofacial

Research and also in collaboration with the

American Dental Association Health Foundation

Paffenbarger Research Center, NIST is providing

the dental industry with a fundamental knowledge

base that will aid in the prediction of clinical

performance of dental materials.

Joseph M. Antonucci and Sheng Lin–Gibson

I

n contrast to current methods that rely on

one-specimen-at-a-time measurements, metrologies

based on combinatorial and high-throughput (C&HT)

approaches can accelerate fundamental and applied

research in dental materials. For dental polymers

and their derivatives (sealants, adhesives, restorative

composites), many critical properties depend on the

chemical, structural, and compositional nature of the

initial monomer (resin) system. For multiphase dental

materials, e.g., composites, similar factors govern the

quality of the interphase between the silanized filler phase

and the resin matrix. The objective of this research was

to determine the feasibility of adapting C&HT techniques

to measure material properties and screen various

experimental resin chemistries for molecular design of

novel dental polymers and composites. The technologies

developed to enable this research include nanoindentation

and the fabrication of single component or multi-variable

discrete and continuous gradient films.

instability for mechanical measurements test. SIEBIMM

on PMMA, a linear polymer, yielded a modulus comparable

to that obtained by the 3-point bend test. Buckling patterns

from cross-linked BisGMA/TEGDMA films (Figure 1)

resulted in moduli with increased variability, i.e., the

buckling patterns were not straight, parallel lines.

Reasons for this behavior are under study.

Figure 2: Elastic moduli of photopolymerized BisGMA-TEGDMA

of different compositions as a function of irradiation time

(represented as distance).

Figure 1: Buckling patterns of BisGMA-TEGDMA in mass

ratios of 30:70 (left) and 70:30 (right).

BisGMA-TEGDMA networks with 2D gradients,

varying in monomer composition and conversion,

were fabricated with a broad conversion range for all

monomer compositions. Conversions were measured

using near-IR spectroscopy, and elastic modulus and

hardness. As shown in Figure 2, the conversion and

the mechanical properties correlated well.

Additional techniques with the potential for C&HT

approaches are being evaluated for their ability to screen

other properties of dental materials, including the interfacial

silane chemistry and cellular response. Studies on the

interfacial chemistry have shown that covalent bonding

of nanoparticles with the polymerized matrix resulted

in well-dispersed composites. To screen the biological

response to dental materials, methods to measure cell

viability, apoptosis, and gene expression levels as a

function of vinyl conversion have been developed.

Contributors and Collaborators

E.A. Wilder, K.S. Wilson, N.J. Lin, C.M. Stafford,

L. Henderson (Polymers Division, NIST);

P.L. Votruba–Drzal (Materials and Construction

Research Division, NIST)

 Among the different resin chemistries under

investigation, 2D compositional gradients using BisGMATEGDA were selected as the benchmark for developing

metrologies and rapid screening techniques for optimizing

hardness, shrinkage, and biocompatibility. The elastic

modulus was determined by two methods, nanoindentation

and SIEBIMM — a strain-induced elastic buckling
37

Safety and Reliability

from the macro to the micro. The scope of activities

includes the development and innovative use of

state-of-the-art measurement systems; leadership in

the development of standardized test procedures and

traceability protocols; development of an understanding

of materials in novel conditions; and development and

certification of Standard Reference Materials® (SRMs).

Many of the tests involve extreme conditions, such as

high rates of loading, high temperatures, or unusual

environments (e.g., deep underwater). These extreme

conditions often produce physical and mechanical

properties that differ significantly from handbook values

for their bulk properties under traditional conditions.

These objectives will be realized through innovative

materials property measurement and modeling.

We take for granted that the physical infrastructure

around us will perform day in and day out with

consistent reliability. Yet, failures occur when these

structures degrade to where they no longer sustain their

design loads, or when they experience loads outside

their original design considerations. In addition, we

have become increasingly aware of our vulnerability to

intentional attacks. The Safety and Reliability Program

within MSEL was created to develop measurement

technology to clarify the behavior of materials under

extreme and unexpected loadings, to assess integrity

and remaining life, and to disseminate guidance and

tools to assess and reduce future vulnerabilities.

Project selection is guided by identification and

assessment of the particular vulnerabilities within

our materials-based infrastructure, and focusing on

those issues that would benefit strongly by improved

measurements, standards, and materials data. This year,

we have worked with the Department of Homeland

Security and the Office of Science and Technology

Policy in developing the National Critical Infrastructure

R&D Plan, which will provide guidance across much

of the national infrastructure. Ultimately, our goal is

to moderate the effects of acts of terrorism, natural

disasters, or other emergencies, all through improved

use of materials.

Our vision is to be the key resource within the

Federal Government for materials metrology

development as realized through the following

objectives:

■ Develop advanced measurement methods needed by

industry to address reliability problems that arise with

the development of new materials;

■ Develop and deliver standard measurements and data;

■ Identify and address vulnerabilities and needed

improvements in U.S. infrastructure; and

■ Support other agency needs for materials expertise.

This program responds both to customer requests

(primarily other government agencies) and to the

Department of Commerce 2005 Strategic Goal of

“providing the information and framework to enable

the economy to operate efficiently and equitably.”

For example, engineering design can produce safe

and reliable structures only when the property data

for the materials are available and accurate. Equally

important, manufacturers and their suppliers need to

agree on how material properties should be measured.

The Safety and Reliability Program works toward

solutions to measurement problems on scales ranging

The MSEL Safety and Reliability Program is

also contributing to the development of test method

standards through committee leadership roles in

standards development organizations such as the

ASTM International and the International Standards

Organization (ISO). In many cases, industry also

depends on measurements that can be traced to

NIST SRMs.

In addition to the activities above, MSEL provides

assistance to various government agencies on homeland

security and infrastructural issues. Projects include

assessing the performance of structural steels as part of

the NIST World Trade Center Investigation, collaborating

with both the Department of Transportation and the

Department of Energy on pipeline safety and bridge

integrity issues, advising the Bureau of Reclamation on

metallurgical issues involving pipelines and dams, and

advising the Department of the Interior on the structural

integrity of the U.S.S. Arizona Memorial.

Contact: Chad R. Snyder

Program Overview
38

Polymer Reliability and Threat Mitigation

This project is developing metrologies and

predictive models to test and predict the long-term

reliability of polymers used in ballistic resistant

armor and machine readable travel documents.

Use of these methods and models will enable one

to monitor the performance of polymeric materials

while in use, elucidate how environmental and

mechanical factors influence performance, and

provide a basis for estimating durability and

establishing care procedures.

Chad R. Snyder, Gale A. Holmes, and

Walter G. McDonough

Ballistic Resistant Armor

I

n response to an apparent failure of ballistic resistant

 armor during first responder use, NIST’s Office of Law

Enforcement Standards initiated a research program

designed to strengthen the certification process of these

protective devices. We are working to identify and develop

analytical metrologies for quantifying the mechanical

properties and degradation pathways of ballistic fibers that

comprise this armor, with the ultimate goal being an

estimate of vest durability and care procedures.

as quantified through the method of Cuniff and

Auerbach.[1] Ongoing research is examining the effects

of fold radius as well as the effects of repeated folding.

Complementing our mechanical properties studies,

our research into the degradation pathways of PBO

and PBO-like materials has made significant headway.

In addition to completion of our review article,[2]

we have synthesized the model compounds

2-phenylbenzoxazole and bis-1,4-(2-benzoxazolyl)

phenylene, and their hydroxy analogs, and we are

currently analyzing, through matrix assisted laser

desorption/ionization (MALDI) mass spectrometry,

the degradation products resulting from exposure to

our newly acquired solar simulator.

Machine Readable Travel Documents

As indicated in an October 14, 2004 press release

from the U.S. Government Printing Office (GPO),

NIST is testing the candidates for the new U.S.

electronic passports for their ability to meet durability,

security, and electronic requirements. This new

technology will eventually be incorporated into

electronic U.S. passports to enhance the security

of millions of Americans traveling around the world.

At the request of the U.S. Department of State, we

participated in the WG3 (Working Group 3 of ISO)

meeting of the Document Durability Task Force for

the EPassport in Tsukuba, Japan. The purpose of the

task force meeting was to update the participants on the

status of the Test Specification for Machine Readable

Travel Documents (MRTD). The main recommendation

from the meeting was that any proposed test specification

by ISO would serve as the guideline to help nations

writing requests for proposals to develop their own

MRTDs. Also, the task force chairs have decided to

use more complex testing sequences to better represent

real-world applications; this was in line with the

recommendations made by NIST.

References

1. P.M. Cunnif and M.A. Averback, 23rd Army Science

Conference, Assistant Secretary of the Army (Acquisition,

Logistics and Technology), Orlando, FL (Dec. 2002).

2. G.A. Holmes, K. Rice, and C.R. Snyder, Journal of

Materials Science, in press.

Contributors and Collaborators

J. Dunkers, C.M. Guttman, K. Flynn, J. Kim,

F.A. Landis, D. Liu, W. Wallace (Polymers Division,

NIST); D. Novotny, J. Guerrieri, G. Koepke, M. Francis,

N. Canales, P. Wilson (Electromagnetics Division, EEEL);

K. Rice (Office of Law Enforcement Standards, EEEL);

T. Dang (Air Force Office of Scientific Research)

This year, we have made considerable progress on

multiple fronts towards these goals for poly(benzoxazole)

(PBO) ballistic fibers. The modified single fiber

fragmentation test, developed last year, was used to

examine the effect of fiber fatigue on ballistic resistance.

Figure 1 shows the effect of folding on the morphology

and mechanical properties of a PBO fiber. Our analysis

suggests that, for this case, folding resulted in an

estimated >10 % reduction in overall ballistic performance,

Figure 1: Top and Left: Micrograph and yield strength data

obtained from modified single fiber test on an unfolded PBO fiber;

Bottom and Right: Micrograph and figure for a folded PBO fiber.

Safety and Reliability
39

Polymers Division FY05 Annual Report Publication List

Polymers Division FY05 Annual Report Publication List

Characterization and Measurement

Characterization

D.L. VanderHart, E. Perez, A. Bello, J. Vasquez,

and R. Quijada, “Effect of Tacticity on the Structure of

Poly(1-octadecane),” Polymer 205, 1877–1885 (2004).

Gelation, Diffusion, and the Glass Transition

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

H.E. Stanley, “Computer Simulation of Dynamical

Anomalies in Stretched Water,” Brazilian Journal of

Physics 34, 24–31 (2004).

K. VanWorkum and J.F. Douglas, “Equilibrium

Polymerization in the Stockmayer Fluid as a Model of

Supermolecular Self-Organization,” Physical Review E

71, 031502 (2004).

Mass Spectrometry

M.A. Arnould, W.E. Wallace, and R. Knochenmuss,

“Understanding and Optimizing the MALDI Process

Using a Heated Sample Stage: a 2,5-Dihydroxybenzoic

Acid Study,” Proceedings of the 52nd ASMS Conference

on Mass Spectrometry and Allied Topics, May 2004,

Nashville, TN.

H.C.M. Byrd, S. Bencherif, B.J. Bauer, K.L. Beers,

Y. Brun, S. Lin–Gibson, and N. Sari, “Examination

of the Covalent Cationization Method Using Narrow

Polydisperse Polystyrene,” Macromolecules 38,

1564–1572 (2005).

K.M. Flynn, S.J. Wetzel, C.M. Guttman,

M.A. Arnould, and L.A. Lewis, “MALDI-TOF-MS

Characterization of Polycyanoacrylate Generated

under Acidic Conditions Using ‘Super Glue’ or

the Cyanoacrylate Finger Print Fuming Method,”

Proceedings of the 52nd ASMS Conference on

Mass Spectrometry and Related Topics, May 2004,

Nashville, TN.

C.M. Guttman, S.J. Wetzel, K.M. Flynn,

B.M. Fanconi, D.L. VanderHart, and W.E. Wallace,

“Matrix-Assisted Laser Desorption/Ionization

Time-of-Flight Mass Spectrometry Interlaboratory

Comparison of Mixtures of Polystyrene with

Different End Groups: Statistical Analysis of Mass

Fractions and Mass Moments,” Analytical Chemistry

77, 4539–4548 (2005).

C.M. Guttman, S.J. Wetzel, K.M. Flynn,

B.M. Fanconi, W.E. Wallace, and D.L. VanderHart,

“International Interlaboratory Comparison of Mixtures

of Polystyrenes with Different End Groups Obtained

by Matrix Assisted Laser Desorption/Ionization

Time-of-Flight Mass Spectrometry (MALDI-TOF-MS):

Preliminary Results,” Proceedings of the 52nd ASMS

Conference on Mass Spectrometry and Allied Topics,

May 2004, Nashville, TN.

A.J. Kearsley, W.E. Wallace, and C.M. Guttman,

“A Numerical Method for Mass Spectral Data Analysis,”

Applied Mathematics Letters 18, 1412–1417 (2005).

Z. Vakili, J.E. Girard, C.M. Guttman, M.A. Arnould,

and H.C.M. Byrd, “Analysis of Covalently Cationized

Polystyrenes Using Liquid Chromatography and

Mass Spectrometry,” Proceedings of the 52nd ASMS

Conference on Mass Spectrometry and Related Topics,

May 2004, Nashville, TN.

W.E. Wallace and C.M. Guttman, “Recent Advances

in Quantitative Synthetic-Polymer Mass Spectrometry

at NIST,” Proceedings of the 52nd ASMS Conference

on Mass Spectrometry and Allied Topics, May 2004,

Nashville, TN.

W.E. Wallace, “Synopsis of the 2004 ASMS Fall

Workshop on Polymer Mass Spectrometry,” Journal

of the American Society for Mass Spectrometry 16,

291–293 (2005).

S.J. Wetzel, C.M. Guttman, K.M. Flynn, and

J.J. Filliben, “The Optimization of MALDI-TOF-MS

for Synthetic Polymer Characterization by Factorial

Design,” Proceedings of the 52nd ASMS Conference

on Mass Spectrometry and Allied Topics, May 2004,

Nashville, TN.

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

“The Influence of Matrix and Laser Energy on the

Molecular Mass Distribution of Synthetic Polymers

obtained by MALDI-TOF-MS,” International Journal

of Mass Spectrometry 238, 215–225 (2004).

Polymers Composites and Nanocomposites

M.Y.M. Chiang, X.F. Wang, and C.R. Schultheisz,

“Prediction and Three-Dimensional Monte-Carlo

Simulation for Tensile Properties of Unidirectional

Hybrid Composites,” Composites Science and

Technology 65, 1719–1727 (2005).
40

X. Wang, M.Y.M. Chiang, and C.R. Snyder,

“Monte-Carlo Simulation for the Fracture Process

and Energy Release Rate of Unidirectional Carbon

Fiber-Reinforced Polymers at Different Temperatures,”

Composites Part A: Applied Science and

Manufacturing 35, 1277–1284 (2004).

S. Bourbigot, D.L. VanderHart, J.W. Gilman,

S. Bellayer, H. Stretz, and D.R. Paul, “Solid State

NMR Characterization and Flammability of

Styrene-Acrylonitrile Copolymer Montmorillonite

Nanocomposite,” Polymer 45, 7627–7638 (2004).

B.H. Cipriano, S.R. Raghavan, and P.M. McGuiggan,

“Surface Tension and Contact Angle Measurements of

a Hexadecyl Imidazolium Surfactant Adsorbed on a

Clay Surface,” Colloid and Surface A: Physiochemical

and Engineering Aspects 262, 8–13 (2005).

Polymer Crystallization

L. Granasy, T. Pusztai, T. Borzsonyi, J.A. Warren,

and J.F. Douglas, “A General Mechanism of

Polycrystalline Growth,” Nature Materials 3,

645–650 (2004).

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

and C.C. Han, “The Effect of Phase Separation on

Crystal Nucleation Density and Lamella Growth

in Near-Critical Polyolefin Blends,” Polymer 45,

5137–5144 (2004).

Electronics Materials

E.K. Lin, Materials Science and Engineering

Laboratory. FY 2004 Programs and Accomplishments:

MSEL Materials for Micro- and Optoelectronics, NIST

Interagency/Internal Report (NISTIR) NISTIR 7129

(2004).

Nanoporous Low-k Dielectric Thin Films

and Dimensional Metrology

B.J. Bauer, “Transformation of Phase Size

Distribution into Scattering Intensity,” Journal of

Polymer Science: Part B Polymer Physics 42,

3070–3080 (2004).

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

D.W. Liu, “Determination of Pore Size Distribution in

Nano-Porous Thin Films from Small Angle Scattering,”

Materials Research Society Symposium Proceedings,

April 2003, San Francisco, CA.

R.C. Hedden, B.J. Bauer, and H.J. Lee,

“Characterization of Nanoporous Low-k Thin

Films by Contrast Match SANS,” Materials Research

Society Symposium Proceedings, April 2003,

San Francisco, CA.

R.C. Hedden, C. Waldfried, H.-J. Lee, and

O. Escorcia, “Comparison of Curing Processes for

Porous Dielectrics — Measurement from Specular

X-ray Reflectivity,” Journal of the Electrochemical

Society 151, F178–F181 (2004).

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

B.J. Bauer, W.L. Wu, and E.K. Lin, “X-ray and

Neutron Porosimetry as Powerful Methodologies for

Determining Structural Characteristics of Porous

Low-k Thin Films,” Proceedings of the International

Interconnect Technology Conference (IITC) 2004

Conference, June 2004, San Francisco, CA.

C.L. Soles, H.J. Lee, R.C. Hedden, D.W. Liu,

B.J. Bauer, and W.L. Wu, “X-ray Reflectivity as a

Powerful Metrology to Characterize Pores in Low-k

Dielectric Films,” Polymers for Microelectronics and

Nanoelectronics, 874, 209–222 (2004).

C.L. Soles, H.J. Lee, E.K. Lin, and W.L. Wu,

Pore Characterization in Low-k Dielectric Films Using

X-ray Reflectivity: X-ray Porosimetry, NIST Special

Publication 960–13 (2004).

B.D. Vogt, R.A. Pai, H.J. Lee, R.C. Hedden,

C.L. Soles, W.L. Wu, E.K. Lin, B.J. Bauer, and

J.J. Watkins, “Characterization of Ordered Mesoporous

Silica Films Using Small-Angle Neutron Scattering

and X-ray Porosimetry,” Chemistry of Materials 17,

1398–1408 (2005).

B.D. Vogt, H.J. Lee, W.L. Wu, and Y. Liu, “Specular

X-ray Reflectivity and Small Angle Neutron Scattering

for Structure Determination of Ordered Mesoporous

Dielectric Films,” Journal of Physical Chemistry B 109,

18445–18450 (2005).

T. Hu, R.L. Jones, W.L. Wu, E.K. Lin, Q. Lin,

D. Keane, S. Weigand, and J. Quintana, “Small Angle

X-ray Scattering Metrology for Sidewall Angle and

Cross Section of Nanometer Scale Line Gratings,”

Journal of Applied Physics 96, 1983–1987 (2004).

Advanced Lithography Fundamentals

E.L. Jablonski, V.M. Prabhu, S. Sambasivan,

E.K. Lin, D.A. Fischer, D.L. Goldfarb, M. Angelopoulos,

and H. Ito, “Surface and Bulk Chemical Properties

of 157 nm Chemically Amplified Polymer Blends,”

Proceedings of the 13th International Conference

on Photopolymers, October 2003, Tamiment, PA.

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

M. Angelopoulos, B.C. Trinque, G.M. Schmidt,

M.D. Stewart, and C.G. Willson, “Formation of

Deprotected ‘Fuzzy Blobs’ in Chemically Amplified

Resists,” Journal of Polymer Science Part B —

Polymer Physics 42, 3063–3069 (2004).

Polymers Division FY05 Annual Report Publication List
41

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,” Polymers for

Microelectronics and Nanoelectronics 874, 86–97

(2004).

J. Lenhart, D. Fischer, S. Sambasivan, E. Lin,

R. Jones, C. Soles, W.L. Wu, D. Goldfarb, and

M. Angelopoulos, “X-Ray Absorption Spectroscopy to

Probe Surface Composition and Surface Deprotection

in Photoresist Films,” Langmuir 21, 4007– 4015 (2005).

V.M. Prabhu, E.J. Amis, D.P. Bossev, and

N.S. Rosov, “Counterion Associative Behavior with

Flexible Polyelectrolytes,” Journal of Chemical Physics

121, 4424–4429 (2004).

V.M. Prabhu, M.X. Wang, E.L. Jablonski, C.L. Soles,

B.D. Vogt, R.L. Jones, E.K. Lin, W.L. Wu, D.L. Goldfarb,

M. Angelopoulos, and H. Ito, “Dissolution Fundamentals

in Model 248 nm and 157 nm Photoresists,” Proceedings

of the 13th International Conference on Photopolymers,

October 2003, Tamiment, PA.

V.M. Prabhu, M.X. Wang, E.L. Jablonski,

B.D. Vogt, E.K. Lin, W.L. Wu, D.L. Goldfarb,

M. Angelopoulos, and H. Ito, “Fundamentals of

Developer-Resist Interactions for Line-Edge Roughness

and Critical Dimensions Control in Model 248 nm and

157 nm Photoresists,” Proceedings of the SPIE,

February 2004, Santa Clara, CA.

V.M. Prabhu, “Counterion Structure and Dynamics

in Polyelectrolyte Solutions,” Current Opinion in

Colloid and Interface Science 10, 2–8 (2005).

V.M. Prabhu, B.D. Vogt, W.-L. Wu, E.K. Lin,

J.F. Douglas, S.K. Satija, D.L. Goldfarb, and H. Ito,

“In Situ Measurement of the Counterion Distribution

within Ultrathin Photoresist Solid Films by ZeroAverage Contrast Specular Neutron Reflectivity,”

Langmuir 21, 6647–6651 (2005).

G.M. Schmid, M.D. Stewart, C.Y. Wang, B.D. Vogt,

V.M. Prabhu, E.K. Lin, and C.G. Willson, “Resolution

Limitation in Chemically Amplified Photoresist

Systems,” Proceedings of SPIE — Advances in Resist

Technology and Processing, XXI, February 2004,

Santa Clara, CA.

B.D. Vogt, E.K. Lin, W.L. Wu, and C.C. White,

“Effect of Film Thickness on the Validity of the

Sauerbrey Equation for Hydrated Polyelectrolyte

Films,” Journal of Physical Chemistry B 108,

12685–12690 (2004).

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

P.M. McGuiggan, J.F. Douglas, E.K. Lin, W.L. Wu,

S.K. Satija, D.L. Goldfarb, and M. Angelopoulos,

“Water Immersion of Model Photoresists: Interfacial

Influences on Water Concentration and Surface

Morphology,” Microlithography, Microfabrication

and Microsystems 4, 013003 (2005).

B.D. Vogt, C.L. Soles, V.M. Prabhu, S.K. Satija,

E.K. Lin, and W.L. Wu, “Water Distribution within

Immersed Polymer Films,” Proceeding of the SPIE

Microlithography 2005, 9, San Jose, CA, 2005.

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

“Dynamics of Thin Polymer Films: Recent Insights

from Incoherent Neutron Scattering,” Journal of

Polymer Science Part B — Polymer Physics 42,

3218–3234 (2004).

D.L. VanderHart, V.M. Prabhu, and E.K. Lin,

“Proton NMR Determination of Miscibility in a Bulk

Model Photoresist System: Poly(4-hydroxystyrene) and

the Photoacid Generator, Di-(t-butylphenyl) Iodonium

Perfluorooctanesulfonate,” Chemistry of Materials 16,

3074–3084 (2004).

Organic Electronics/Dielectric Measurements

J. Obrzut and A. Anopchenko, “Input Impedance

of a Coaxial Line Terminated with a Complex Gap

Capacitance — Numerical and Experimental Analysis,”

IEEE Transactions on Instrumentation and

Measurement 53, 1197–1201 (2004).

J. Obrzut and K. Kano, “Impedance and Nonlinear

Dielectric Testing at High AC Voltages Using

Waveforms,” IEEE Transactions on Intrumentation

and Measurement 54, 1570–1574 (2005).

B.D. Vogt, H.-J. Lee, V.M. Prabhu,

D.M. DeLongchamp, S.K. Satija, E.K. Lin,

and W.L. Wu, “X-Ray and Neutron Reflectivity

Measurements of Moisture Transport Through Model

Multilayered Barrier Films for Flexible Displays,”

Journal of Applied Physics 97, 114509 (2005).

B.D. Vogt, V.M. Prabhu, C.L. Soles, S.K. Satija,

E.K. Lin, and W.L. Wu, “Control of Moisture at Buried

Polymer/Alumina Interfaces through Substrate Surface

Modification,” Langmuir 21, 2460–2464 (2005).

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

W.L. Wu, “Moisture Absorption into Ultrathin

Hydrophilic Polymer Films on Different Substrate

Surfaces,” Polymer 46, 1635–1642 (2005).

Polymers Division FY05 Annual Report Publication List
42

Biomaterials

Combinatorial Libraries for Rapid Screening

E.J. Amis, S.B. Kennedy, A.M. Forster, and

N.R. Washburn, “Spatial Correlations and Robust

Statistical Analysis for Combinatorial Methodologies,”

Proceedings of the 7th World Biomaterials Congress,

478, May 2004, Sidney, Australia.

E.J. Amis, N.R. Washburn, C.G. Simon, Jr., and

S.B. Kennedy, “Gradient Libraries for Combinatorial

and High-Throughput Investigations of Polymeric

Biomaterials,” Proceedings of the 7th World Biomaterials

Congress, 1265, May 2004, Sidney, Australia.

N. Eidelman and C.G. Simon, Jr., “Characterization

of Combinatorial Polymer Blend Composition

Gradients by FTIR Microspectroscopy,” Journal of

Research of the National Institute of Standards and

Technology 109, 219–231 (2004).

N.J. Lin, L.O. Bailey, and N.R. Washburn,

“Combinatorial Methods to Assess Cellular Response

to Bis-GMA/TEGDMA Vinyl Conversion Levels,”

Society for Biomaterials 30th Annual Meeting and

Exposition.

Y. Mei, T. Wu, C. Xu, K.J. Langenbach, J.T. Elliott,

B.D. Vogt, K.L. Beers, E.J. Amis and N.R. Washburn,

“Combinatorial Studies of the Effect of Polymer

Grafting Density on Protein Absorption and Cell

Adhesion,” ACS Polymer Preprints, Washington, DC,

2005.

N.R. Washburn, M.D. Weir, W.J. Li, and R.S. Tuan,

“Combinatorial Screening of Chondrocyte Response to

Tissue Engineering Hydrogels,” Proceedings of the

7th World Biomaterials Congress, 1269, May 2004,

Sidney, Australia.

Bioanalysis of Polymeric Materials

M.L. Becker, L.O. Bailey, N.R. Washburn, J. Kohn,

and E.J. Amis, “Gene Expression Profiles of Cells

in Response to Tyrosine Polycarbonate Blends,”

The 7th New Jersey Symposium on Biomaterials

Science, October 2004, New Brunswick, NJ.

M.L. Becker, L.O. Bailey, and K.L. Wooley,

“Peptide-Derivatized Shell-Cross-linked Nanoparticles.

2. Biocompatibility Evaluation,” Bioconjugate

Chemistry 15, 710–717 (2004).

M.L. Becker, L.O. Bailey, J.S. Stephens, A. Rege,

J. Kohn, and E.J. Amis, “Cellular Response to

Phase-Separated Blends of Tyrosine-Derived

Polycarbonates,” Polymer Material Science and

Engineering (PMSE) Preprint, Washington, DC, 2005.

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

F.A. Landis, and J.A. Cooper, “Optical Coherence

Microscopy for In-situ Monitoring of Cell Growth

in Scaffold Constructs,” Proceedings of the 7th World

Biomaterials Congress, 584, May 2004, Sidney,

Australia.

M.T. Cicerone, W.J. Li, R. Tuan, C.L. Soles, and

B.M. Vogel, “Sustained Delivery of Stabilized Proteins

from Electrospun Tissue Scaffolds,” Proceedings of

the 7th World Biomaterials Congress, 514, May 2004,

Sidney, Australia.

T. Dutta Roy, J.J. Stone, E.H. Cho, S.J. Lockett, and

F.W. Wang, “Mechanisms of Osteoblast Adhesion on

3D Polymer Scaffolds Made by Rapid Prototyping,”

Society for Biomaterials 30th Annual Meeting

Transactions, 347, April 2005, Memphis, TN.

T. Dutta Roy, J.J. Stone, W. Sun, E.H. Cho,

S.J. Lockett, F.W. Wang, and L. Henderson, “Osteoblast

Adhesion on Tissue Engineering Scaffolds Made by

Bio-Manufacturing Techniques,” Proceedings of 2005

American Society of Mechanical Engineers (ASME)

International Mechanical Engineering Congress and

Exposition (IMECE), November 2005, Orlando, FL.

E. Jabbari, K.W. Lee, A.C. Ellison, M.J. Moore,

J.A. Tesk, and M.J. Yaszemski, “Fabrication of Shape

Specific Biodegradable Porous Polymeric Scaffolds

with Controlled Interconnectivity by Solid Free-Form

Microprinting,” Transactions of the 7th World

Biomaterials Congress, 1348, May 2004, Sidney,

Australia.

T.W. Kee and M.T. Cicerone, “A Simple Approach

to One-Laser, Broadband Coherent Anti-Stokes Raman

Scattering Microscopy,” Optics Letters 29, 2701–2703

(2004).

C.A. Khatri, G. Du, E.S. Wu, and F.W. Wang,

“Focal Adhesions of Osteoblasts on Poly(D,L-lactide)/

Poly(vinyl alcohol) Blends by Confocal Fluorescence

Microscopy,” Proceedings of the 7th World

Biomaterials Congress, 609, May 2004, Sidney,

Australia.

Y. Mei, T. Wu, C. Xu, K. Langenbach, J.T. Elliott,

K.L. Beers, E.J. Amis, N.R. Washburn, and

L. Henderson, “Control of Protein Absorption and

Cell Adhesion: Effect of Polymer Grafting Density,”

ACS Polymer Preprints, Washington, DC, 2005.

S.N. Park, E.S. Wu, C.A. Khatri, H. Suh, and

F.W. Wang, “Microstructures of Collagen-Hyaluronic

Acid Hydrogels by Two-Photon Fluorescence

Microscopy,” Proceedings of the 7th World

Biomaterials Congress, 1496, May 2004, Sidney,

Australia.

Polymers Division FY05 Annual Report Publication List
43

C.G. Simon, Jr., “Imaging Cells on Polymer

Spherulites,” Journal of Microscopy 216, 153–155

(2004).

J.A. Tesk, “ASTM Task Force Open for

Development of Reference Scaffolds for Tissue

Engineered Medical Products (TEMPs),”

Biomaterials FORUM 26, 14 (2004).

N.R. Washburn, M.D. Weir, F.W. Wang, and

L.O. Bailey, “Measurement and Modulation of

Cytokine Profiles Induced by Biomaterials,”

Proceedings of the 7th World Biomaterials Congress,

1339, May 2004, Sidney, Australia.

H.H.K. Xu and C.G. Simon, Jr., “Fast Setting

Calcium Phosphate-Chitosan Scaffold: Mechanical

Properties and Biocompatibility,” Biomaterials 26,

1337–1348 (2005).

H.H.K. Xu, C.G. Simon, Jr., S. Takagi, L.C. Chow,

and F.C. Eichmiller, “Strong, Macroporous and In-Situ

Hardening Hydroxyapatite Scaffold for Bone Tissue

Engineering,” Biomaterials Forum 27, 14–19 (2005).

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

and F.W. Wang, “In Vitro Biocompatibility of

Hydrolytically Degraded Poly(D,L-lactic acid),”

Proceedings of the 7th World Biomaterials Congress,

1324, May 2004, Sidney, Australia.

K. Zhang, N.R. Washburn, J.M. Antonucci, and

C.G. Simon, Jr., “In Vitro Culture of Osteoblasts with

Three Dimensionally Ordered Macroporous Sol-gel

Bioactive Glass (3DOM-BG) Particles,” International

Symposium on Ceramics in Medicine (Bioceramics 17),

December 2004, New Orleans.

K. Zhang, N.R. Washburn, and C.G. Simon, Jr.,

“Cytotoxicity of Three-Dimensionally Ordered

Macroporous Sol–Gel Bioactive Glass (3DOM-BG),”

Biomaterials 26, 4532– 4539 (2005).

Molecular Advances in Dental Materials

L.E. Carey, H.H.K. Xu, C.G. Simon, Jr., S. Takagi,

and L.C. Chow, “Premixed Rapid-Setting Calcium

Phosphate Composites for Bone Repair,” Biomaterials

26, 5002–5014 (2005).

M. Farahani, J.M. Antonucci, and C.M. Guttman,

“Analysis of the Interactions of a Trialkoxysilane with

Dental Monomers by MALDI-TOF Mass Spectrometry,”

ACS Polymer Preprints, August 2004, Philadelphia, PA.

S. Lin–Gibson, “The Use of MALDI-TOF MS and

1H NMR as Complimentary Methods for Confirming

Composition and Purity of Hydrogel Prepolymers,”

Biomaterials FORUM 26, 10–11 (2004).

S. Lin–Gibson, M.L. Becker, K.S. Wilson, and

N.R. Washburn, “Synthesis and Characterization of

Bioactive PEGDM Hydrogels,” ACS Polymer

Preprints, August 2004, Philadelphia, PA.

S. Lin–Gibson, E.A. Wilder, F.A. Landis,

and P.L. Drzal, “Combinatorial Methods for the

Characterization of Dental Materials,” ACS PMSE

Preprint, Washington, DC.

C.G. Simon, Jr., J.M. Antonucci, D.W. Liu, and

D. Skrtic, “In Vitro Cytotoxicity of Amorphous

Calcium Phosphate Composites,” Biomaterials 20,

279–295 (2005).

E.A. Wilder, J.B. Quinn, and J.M. Antonucci,

“Organogelators and their Application in Dental

Materials,” ACS Polymer Preprints, August 2004,

Philadelphia, PA.

E.A. Wilder, K.S. Wilson, J.B. Quinn, D. Skrtic,

and J.M. Antonucci, “Effect of an Organogelator on

the Properties of Dental Composites,” Chemistry of

Materials 17, 2946–2952 (2005).

K.S. Wilson and J.M. Antonucci, “Structure–

Property Relationships of Thermoset Methacrylate

Composites for Dental Materials: Study of the

Interfacial Phase of Silica Nanoparticle-Filled

Composites,” ACS Polymer Preprints, August 2004,

Philadelphia, PA.

K.S. Wilson, K. Zhang, and J.M. Antonucci,

“Systematic Variation of Interfacial Phase Reactivity in

Dental Nanocomposites,” Biomaterials 26, 5095–5103

(2005).

K. Zhang, N.R. Washburn, C.G. Simon, Jr.,

J.M. Antonucci, and S. Lin–Gibson, “In Situ Formation

of Blends by Photopolymerization of Poly(Ethylene

Glycol) Dimethacrylate (PEGDMA) and Polylactide

(PLA),” Biomacromolecules 6, 1615–1622 (2005).

Multiphase Materials

Nanothin Film Stability and Wetting

H. Grull, L.P. Sung, A. Karim, J.F. Douglas,

S.K. Satija, M. Hayashi, H. Jinnai, T. Hashimoto, and

C.C. Han, “Finite Size Effects on Surface Segregation

in Polymer Blend Films Above and Below the Critical

Point of Phase Separation,” Europhysics Letters 65,

671–677 (2004).

K.M. Ashley, D. Raghavan, J.F. Douglas, and

A. Karim, “Mapping Wetting/Dewetting Transition

Line in Ultrathin Polystyrene Films Combinatorially,”

ACS PMSE Preprints, Washington, D.C.

Polymers Division FY05 Annual Report Publication List
44

R. Song, M.Y.M. Chiang, A.J. Crosby, A. Karim,

E.J. Amis, and N. Eidelman, “Combinatorial Peel Tests

for the Characterization of Adhesion Behavior of

Polymeric Films,” Polymer 46, 1643–1652 (2005).

M.Y.M. Chiang, R. Song, A.J. Crosby, A. Karim,

C.K. Chiang, and E.J. Amis, “Combinatorial Approach

to the Edge Delamination Test for Thin Film Reliability

— Adaptability and Variability,” Thin Solid Films 476,

379–385 (2005).

Processing Characterization

Nanomanufacturing

S.D. Hudson, F.R. Phelan, Jr., M.D. Handler,

J.T. Cabral, K.B. Migler, and E.J. Amis, “Microfluidic

Analogue of the 4-Roll Mill,” Applied Physics Letters

85, 335–337 (2004).

S.D. Hudson, J.T. Cabral, W. Zhang, J.A. Pathak,

and K.L. Beers, “Microfluidic Interfacial Tensiometry,”

ACS PMSE Preprints, Washington, DC.

F.R. Phelan, Jr., S.D. Hudson, and M.D. Handler,

“Fluid Dynamics Analysis of Channnel Flow

Geometries for Materials Characterization in

Microfluidic Devices,” Rheologica Acta 45, 59–71

(2005).

J.A. Pathak, D.J. Ross, and K.B. Migler, “Elastic

Flow Instability, Curved Streamlines and Mixing in

Microfluidic Flows,” Physics of Fluids 16, 4028–4034

(2004).

V. Percec, A.E. Dulcey, V.S.K. Balagurusamy,

Y. Miura, J. Smidrkal, M. Peterca, S. Nummelin,

U. Edlund, S.D. Hudson, P.A. Heiney, D.A. Hu,

S.N. Magonov, and S.A. Vinogradov, “Self-Assembly

of Amphiphilic Dendritic Dipeptides into Helical

Pores,” Nature 430, 764–768 (2004).

K. Van Workum, K. Yoshimoto, J.J. de Pablo, and

J.F. Douglas, “Isothermal Stress and Elasticity Tensors

for Ions and Point Dipoles Using Ewald Summations,”

Physical Review E 71, 061102 (2005).

Polymer and Nanoclay Processing

A.J. Bur, Y.H. Lee, S.C. Roth, and P.R. Start,

“Polymer/Clay Nanocomposites Compounding:

Establishing an Extent of Exfoliation Scale Using

Real-Time Dielectric, Optical and Fluorescence

Monitoring,” ACS Polymer Preprints, August 2004,

Philadelphia, PA.

A.J. Bur, S.C. Roth, M.A. Spalding, D.W. Baugh,

K.A. Koppi, and W.C. Buzanowski, “Temperature

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

Polymer Engineering and Science 44, 2148–2157

(2004).

R.D. Davis, A.J. Bur, M. McBrearty, Y.-H. Lee,

J.W. Gilman, and P.R. Start, “Dielectric Spectroscopy

During Extrusion Processing of Polymer Nanocomposites:

A High Throughput Processing/Characterization

Method to Measure Layered Silicate Content and

Exfoliation,” Polymer 45, 6487–6493 (2004).

Y.-H. Lee, A.J. Bur, S.C. Roth, and P.R. Start,

“Impact of Exfoliated Silicate on the Dielectric

Relaxation of Nylon 11 Nanocomposites in the Melt

and Solid States,” ACS PMSE Preprints, August 2004,

Philadelphia, PA.

Y.-H. Lee, A.J. Bur, S.C. Roth, and P.R. Start,

“Accelerated Alpha Relaxation Dynamics in the

Exfoliated Nylon 11/Clay Nanocomposite Observed

in the Melt and Semi-Crystalline State By Dielectric

Spectroscopy,” Macromolecules 38, 3828–3837 (2005).

Y.-H. Lee, A.J. Bur, S.C. Roth, P.R. Start, and

R.H. Harris, “Monitoring the Relaxation Behavior

of Nylon/Clay Nanocomposites in the Melt with an

Online Dielectric Sensor,” Polymers for Advanced

Technologies 16, 249–256 (2005).

N. Noda, Y.-H. Lee, A.J. Bur, V.M. Prabhu,

C.R. Snyder, S.C. Roth, and M. McBrearty,

“Dielectric Properties of Nylon 6/Clay Nanocomposites

from On-Line Process Monitoring and Off-Line

Measurements,” Polymer 46, 7201–7217 (2005).

W.J. Wang, S.B. Kharchenko, K.B. Migler, and

S. Zhu, “Triple-Detector GPC Characterization and

Processing Behavior of Long-Chain-Branched

Polyethylene Prepared by Solution Polymerization

with Constrained Geometry Catalyst,” Polymer 45,

6495–6505 (2004).

Nanotubes

D. Fry, B. Langhorst, H. Kim, E.A. Grulke,

H. Wang, and E.K. Hobbie, “Anisotropy Of Sheared

Carbon Nanotube Suspensions, Physical Review Letters

95, 038304 (2005).

E.K. Hobbie, “Optical Anisotropy of Nanotube

Suspensions,” Journal of Chemical Physics 121,

1029–1037 (2004).

S.B. Kharchenko, J.F. Douglas, J. Obrzut,

E.A. Grulke, and K.B. Migler, “Flow-induced

Properties of Nanotube-Filled Polymer Materials,”

Nature Materials 3, 564 –568 (2004).

P.M. McGuiggan, “Friction and Adhesion

Measurements between a Fluorocarbon Surface and a

Hydrocarbon Surface in Air,” Journal of Adhesion 80,

395– 408 (2004).

Polymers Division FY05 Annual Report Publication List
45

H. Wang, W. Zhou, D.L. Ho, K.L. Winey,

J.E. Fischer, C.J. Glinka, and E.K. Hobbie, “Dispersing

Single-Wall Carbon Nanotubes with Surfactants:

A Small Angle Neutron Study,” Nanoletters 4,

1789–1793 (2004).

T. Kashiwagi, F. Du, K.I. Winey, K.M. Groth,

J.R. Shields, S.P. Bellayer, H. Kim, and J.F. Douglas,

“Flammability Properties of Polymer Nanocomposites

with Single-walled Carbon Nanotubes: Effects of

Nanotube Dispersion and Concentration,” Polymer 46,

471– 481 (2005).

Multivariant Measurement Methods

Combinatorial Methods Development

W. Zhang, M.J. Fasolka, A. Karim, and E.J. Amis,

“An Informatics Infrastructure for Combinatorial and

High-Throughput Materials Research Built on Open

Source Code,” Measurement Science and Technology

16, 261–269 (2005).

S. Ludwigs, K. Schmidt, C.M. Stafford,

M.J. Fasolka, A. Karim, E.J. Amis, R. Magerle, and

G. Krauch, “Combinatorial Mapping of the Phase

Behavior of ABC Triblock Terpolymers in Thin Films:

Experiments,” Macromolecules 38, 1850–1858 (2005).

D. Julthongpiput, W. Zhang, and M.J. Fasolka,

“Combinatorial and High-Throughput Microscopy for

Thin Film Research,” Proceedings Microscopy and

Microanalysis, 2004 (Savannah, GA).

Adhesion and Mechanical Properties

M.Y.M. Chiang, D. Kawaguchi, and C.M. Stafford,

“Combinatorial Approaches for Characterizing Thin

Film Bond Strength,” The Symposium Combinatorial

Approaches to Materials, the American Chemical

Society (ACS), Washington, DC.

M.Y.M. Chiang, C.M. Stafford, R. Song, and

A.J. Crosby, “High-Throughput Approach to Study

the Effects of Polymer Annealing Temperature and Time

on Adhesion,” Proceedings of 28th Annual Meeting of

Adhesion Society, 205–207, Mobile, AL.

A. Chiche, W. Zhang, C.M. Stafford, and A. Karim,

“A New Design for High-Throughput Peel Tests:

Statistical Analysis and Example,” Measurement

Science and Technology 16, 183–190 (2005).

A.J. Crosby, M.J. Fasolka, and K.L. Beers,

“High-Throughput Craze Studies in Gradient Thin

Films Using Ductile Copper Grids,” Macromolecules

37, 9968–9974 (2004).

A.M. Forster, W. Zhang, and C.M. Stafford,

“A Multilens Measurement Platform for

High-Throughput Adhesion Measurements,”

Measurement Science and Technology 16, 81–89

(2005).

A.M. Forster, W. Zhang, and C.M. Stafford,

“The Development of a High-Throughput Axisymmetric

Adhesion Test,” Proceedings of the 28th Annual

Meeting of Adhesion Society, 399–401, Mobile, AL.

S. Guo, M.Y. Chiang, and C.M. Stafford, “Elastic

Instability of Multilayer Films Coated on Substrates,”

Proceedings of the 28th Annual Meeting of Adhesion

Society, 67–69, Mobile, AL.

S. Guo, C.M. Stafford, and M.Y. Chiang, “Stress

Analysis for Combinatorial Buckling-Based Metrology

of Thin Film Modulus,” Proceedings of the 28th

Annual Meeting of Adhesion Society, 236–237,

Mobile, AL.

C. Harrison, C.M. Stafford, W. Zhang, and

A. Karim, “Sinusoidal Phase Grating Created by a

Tunably Buckled Surface,” Applied Physics Letters 85,

4016–4018 (2004).

S. Moon, A. Chiche, A.M. Forster, W. Zhang, and

C.M. Stafford, “Evaluation of Temperature-Dependent

Adhesive Performance via Combinatorial Probe Tack

Measurements,” Review of Scientific Instruments 76,

062210 (2005).

C.M. Stafford, “A New ‘Wrinkle’ in Nanometrology,”

Optical Engineering Magazine, November/December,

48 (2004).

C.M. Stafford, S. Guo, M.Y.M. Chiang, and

C. Harrison, “Combinatorial and High-Throughput

Measurements of the Modulus of Thin Polymer Films,”

Review of Scientific Instruments 76, 062207 (2005).

E.A. Wilder, S. Guo, M.Y. Chiang, and C.M. Stafford,

“High Throughput Modulus Measurements of Soft

Polymer Networks,” ACS Polymer Preprints, ACS Fall

Meeting 2005 (Washington, DC).

Polymer Formulations

K.L. Beers, T. Wu, and C. Xu, “ATRP in

Microchannels,” ACS Polymer Preprints, ACS Fall

Meeting 2005 (Washington, DC).

A.J. Bur, Z.T. Cygan, K.L. Beers, and S.E. Barnes,

“Monitoring Polymerization in Microfluidic Flow

Channels Using Spectroscopy Methods,” Proceedings

of the Annual Technical Meeting, Society of Plastics

Engineers, May 2005 (Boston, MA).

Polymers Division FY05 Annual Report Publication List
46

J.T. Cabral and J.F. Douglas, “Propagating Waves

of Network Formation Induced by Light,” Polymer 46,

4230– 4241 (2005).

J.T. Cabral and A. Karim, “Discrete Combinatorial

Investigation of Polymer Mixture Phase Boundaries,”

Measurement Science and Technology 16, 191–198

(2005).

Z.T. Cygan, J.T. Cabral, K.L. Beers, and E.J. Amis,

“Microfluidic Platform for Generation of Organic Phase

Microreactors,” Langmuir 21, 3629–3634 (2005).

A.I. Norman, D.L. Ho, A. Karim, and E.J. Amis,

“Phase Behavior of Diblock Copoly(ethylene oxidebutylene oxide), E18B9 in Water by Small Angle

Neutron Scattering,” Journal of Colloid and Interface

Science 288, 155–165 (2005).

J.A. Pathak, R.F. Berg, and K.L. Beers,

“Development of a Microfluidic Rheometer for

Complex Fluids,” ACS PMSE Preprints, ACS Fall

Meeting 2005 (Washington, DC).

H.J. Walls, R.F. Berg, and E.J. Amis, “Multi-sample

Couette Viscometer for Polymer Formulations,”

Measurement Science and Technology 16, 137–143

(2005).

T. Wu, Y. Mei, J.T. Cabral, C. Xu, and K.L. Beers,

“A New Synthetic Method for Controlled Polymerization

Using a Microfluidic System,” Journal of the American

Chemical Society 126, 9880–9881 (2004).

T. Wu, Y. Mei, C. Xu, H.C.M. Byrd, and K.L. Beers,

“Block Copolymer PEO-b-PHPMA Synthesis Using

Controlled Radical Polymerization on a Chip,”

Macromolecular Rapid Communications 26,

1037–1042 (2005).

C. Xu, T. Wu, C.M. Drain, J.D. Batteas, and

K.L. Beers, “Microchannel Confined Surface Initiated

Polymerization,” Macromolecules 38, 6–8 (2005).

C. Xu, T. Wu, C.M. Drain, J.D. Batteas, and

 K.L. Beers, “Synthesis of Gradient Copolymer

Brushes via Surface Initiated Atom Transfer Radical

Copolymerization,” ACS Polymer Preprints, ACS Fall

Meeting 2004 (Philadelphia, PA).

Scanned Probe Micropscopy

L.S. Goldner, M.J. Fasolka, and S.N. Goldie,

“Measurement of the Local Diattenuation and

Retardance of Thin Polymer Films Using Near

Field Polarimetry,” Applications of Scanned Probe

Microscopy to Polymers, edited by J.D. Batteas and

G. Walker (American Chemical Society, 2005).

L.S. Goldner, S.N. Goldie, M.J. Fasolka, F. Renaldo,

J. Hwang, and J.F. Douglas, “Near-Field Polarimetric

Characterization of Polymer Crystallites,” Applied

Physics Letters 85, 1338–1340 (2004).

X.H. Gu, T. Nguyen, L.P. Sung, M.R. VanLandingham,

M.J. Fasolka, J.W. Martin, Y.C. Jean, D. Nguyen,

N.K. Chang, and T.Y. Wu, “Advanced Techniques for

Nanocharacterization of Polymeric Coating Surfaces,”

JCT Research 1, 191–200 (2004).

D. Julthongpiput, M.J. Fasolka, and E.J. Amis,

“Gradient Reference Specimens for Advanced Scanned

Probe Microscopy,” Microscopy Today 12, 48–51

(2004).

Nanomaterials

M.J. Fasolka, D. Julthongpiput, W. Zhang, A. Karim,

and E.J. Amis, “Gradient Micropatterns for Surface

Nanometrology and Thin Nanomaterials Development,”

ACS PMSE Preprints, ACS Fall Meeting 2005

(Washington, DC).

D. Julthongpiput, M.J. Fasolka, W. Zhang,

T. Nguyen, and E.J. Amis, “Gradient Chemical

Micropatterns: A Reference Substrate for Surface

Nanometrology,” Nano Letters 8, 1535–1540 (2005).

Y. Park, Y.W. Choi, S. Park, C. Cho, M.J. Fasolka,

and D. Sohn, “Monolayer Formation of PBLG-PEO

Block Copolymers at the Air–Water Interface,” Journal

of Colloid and Interface Science 283, 322–328 (2005).

Polymers Division FY05 Annual Report Publication List
47

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

NIST Fellow

Wen-li Wu

Phone: 301–975–6839

E-mail: wen-li.wu@nist.gov

Group Leaders

Characterization and Measurement

Chad R. Snyder

Electronics Materials

Eric K. Lin

Phone: 301–975–6743

E-mail: eric.lin@nist.gov

Biomaterials

Marcus T. Cicerone

Phone: 301–975–8104

E-mail: marcus.cicerone@nist.gov

Multiphase Materials

Alamgir Karim

Phone: 301–975–6588

E-mail: alamgir.karim@nist.gov

Processing Characterization

Kalman Migler

Phone: 301–975–4876

E-mail: kalman.migler@nist.gov

Multivariant Measurement Methods

Michael Fasolka

Phone: 301–975–8526

E-mail: michael.fasolka@nist.gov
48

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

Combinatorial methods

High-throughput experimentation

Antonucci, Joseph M.

joseph.antonucci@nist.gov

Synthetic polymer chemistry

Dental composites, cements and adhesion

Initiator systems

Interfacial coupling agents

Remineralizing polymer systems

Nanocomposites

Audino, Susan A.+

susan.audino@nist.gov

Mass spectrometry

Bailey, LeeAnn O.

+

leeann.bailey@nist.gov

Cell biology

Apoptosis

Inflammatory responses

Flow cytometry

Polymerase chain reaction

Barnes, Susan E. +

susan.barnes@nist.gov

Vibrational spectroscopy of polymers

Microfluidics technology

Fluorescence spectroscopy

On-line monitoring of polymer melts/extrusion

Bauer, Barry J.

barry.bauer@nist.gov

Polymer synthesis

Polymer chromatography

MALDI mass spectroscopy

Thermal characterization

Neutron, x-ray and light scattering

Dendrimers, metallic ions nanocluster

Porous low-k thin film characterization

Carbon nanotubes

Becker, Matthew L.

matt.becker@nist.gov

Polymer synthesis

Block copolymers

Peptide synthesis

Phage display

Combinatorial methods

Polymerase chain reaction

Beers, Kathryn L.

kathryn.beers@nist.gov

Combinatorial and high-throughput methods

Polymer formulations

Microfluidics technology

Polymer synthesis

Controlled/living polymerizations

Blair, William R.

william.blair@nist.gov

Polymer analysis by size exclusion

chromatography

Mass spectrometry of polymers

High temperature viscometry

Rayleigh light scattering

Extrusion plastometry

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

Cabral, Joao+

joao.cabral@nist.gov

Polymeric rapid prototyping

Polymer phase separation

Millifluidic measurements

Carey, Clifton M.*

clifton.carey@nist.gov

Dental plaque

Microanalytical analysis techniques

Fluoride efficacy for dental health

De- and re-mineralization

Phosphate chemistry

Ion-selective electrodes

Toothpaste abrasion & erosion

Cherng, Maria*

maria.cherng@nist.gov

Calcium phosphate biomaterials

Chiang, Chwan K.

c.chiang@nist.gov

Electroluminescent polymers

Residual stress

Impedance spectroscopy

Research Staff
49

Chiang, Martin Y.M.

martin.chiang@nist.gov

Computational mechanics

(finite element analysis)

Strength of materials, fracture mechanics

Engineering mechanics of polymer-based

materials

Bi-material interface

Image quantitation

Choi, Kwang-Woo+

kwang-woo.choi@nist.gov

Polymers for lithography

Critical dimension small angle x-ray scattering

(CD-SAXS)

Extreme ultraviolet (EUV) lithography

Chow, Laurence C.*

laurence.chow@nist.gov

Calcium phosphate compounds and biomaterials

Tooth demineralization and remineralization

Dental and biomedical cements

Solution chemistry

Dental caries prevention

Cicerone, Marcus T.

marcus.cicerone@nist.gov

Protein stabilization

Glass transition theory

Optical coherence microscopy

Tissue engineering scaffolds

Confocal microscopy

Spectroscopic imaging

Cipriano, Bani H.+

Polymer rheology

Cooper, James A.

james.cooper@nist.gov

Tissue engineering

Polymer scaffolds

Cell biology

Optical microscopy

Cygan, Zuzanna T.

zuzanna.cygan@nist.gov

Polymer formulations

Fluorescent probe studies

Millifluidics of polymer solutions

Combinatorial and high-throughput methods

DeLongchamp, Dean M.

dean.delongchamp@nist.gov

Organic electronics

Polymer thin films

Polyelectrolytes

Near-edge x-ray absorption fine structure

spectroscopy (NEXAFS)

Film electrochemistry

Dickens, Sabine*

sabine.dickens@nist.gov

Dental composites

Dental adhesives

Transmission electron microscopy

Remineralizing resin-based calcium phosphate

composites and cements

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

Dunkers, Joy P.

joy.dunkers@nist.gov

Optical coherence microscopy

Image analysis

Fiber optic spectroscopy

Infrared microspectroscopy of polymers

Confocal fluorescence microscopy

Duppins, Gretchen E.*

gretchen.duppins@nist.gov

Editorial Coordinator

Dutta Roy, Tithi

tithi.duttaroy@nist.gov

Reference scaffolds for tissue engineering

Cellular response to biomaterials

Eichmiller, Frederick C.*

frederick.eichmiller@nist.gov

Clinical dentistry

Composites

Dentin adhesives

Polymerization shrinkage

Eidelman, Naomi B.*

naomi.eidelman@nist.gov

FTIR microspectroscopy

Characterization of dental tissues and materials

Composition of combinatorial polymer blends

Appplication of temperature and UV gradients

to polymers

Research Staff
50

Epps, Thomas H., III

thomas.epps@nist.gov

Combinatorial and high-throughput methods

Block copolymers

Self-assembled structures

Surface energy patterning and control

Surfaces and interfaces

Scanning probe microscopy

Fagan, Jeffrey A.

jeffrey.fagan@nist.gov

Dielectrophoretic separations

Colloidal solutions

Electrooptical effects

Carbon nanotubes

Fasolka, Michael J.

michael.fasolka@nist.gov

Combinatorial and high-throughput methods

NIST Combinatorial Methods Center (NCMC)

Self-assembled structures

Surface energy patterning and control

Surfaces and interfaces

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 (NMR)

Flynn, Kathleen M.

kathleen.flynn@nist.gov

Melt flow rate measurements

Size exclusion chromatography

Mass spectrometry of polymers

Fowler, Bruce O.+

bruce.fowler@nist.gov

Infrared and Raman spectroscopy

Structure of calcium phosphates, bones,

and teeth

Composites

Frukhtbeyn, Stanislav*

stan.frukhtbeyn@nist.gov

Calcium phosphate compounds and biomaterials

Topical dental fluorides

Fry, Dan J.

dan.fry@nist.gov

Particle alignment and dispersion

Carbon nanotubes

Rheology

Gallant, Nathan D.

nathan.gallant@nist.gov

Cell adhesion to biomaterials

Combinatorial screening of bioactive gradients

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

Guo, Shu+

shu.guo@nist.gov

Solid mechanics

Mechanical properties of thin films

Combinatorial and high-throughput methods

Polymer thin films

Surfaces and interfaces

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

Henderson, Lori A.

lori.henderson@nist.gov

Structure–property relationships of biomaterials

Structure–function of tissues

Molecular engineering of DNA and proteins

Cellular physiology and assays

Molecular biology screening

Polymer synthesis and characterization

Hobbie, Erik K.

erik.hobbie@nist.gov

Light scattering and optical microscopy

Dynamics of complex fluids

Shear-induced structures in polymer blends

and solutions

Carbon nanotubes suspensions and melts

Hodkinson, Christine S.*

christine.hodkinson@nist.gov

Manager, Administrative Services

Research Staff
51

Holmes, Gale A.

gale.homes@nist.gov

Composite interface science

Chemical-structure-mechanical property

relationships for:

Polymer chemistry

Mass spectroscopy

Nanocomposites

Ballistic resistance

Hudson, Steven D.

steven.hudson@nist.gov

Electron microscopy

Polymeric surfactant and interfacial dynamics

Self-assembly

Nanoparticle characterization and assembly

Biomaterials

Jones, Ronald L.

ronald.jones@nist.gov

Neutron and x-ray scattering

Nanoimprint lithography

Neutron reflectivity

Polymer surfaces and thin films

Polymer phase transitions and computer

simulation

Julthongpiput, Duangrut+

duangrut.julthongpiput@nist.gov

Combinatorial and high-throughput methods

Polymer adhesion and mechanical properties

Scanning probe microscopy

Jung, Youngsuk+

youngsuk.jung@nist.gov

Organic electronics

Polymer thin films and interfaces

Kang, Shuhui+

skang@nist.gov

Fourier transform infrared spectroscopy (FTIR)

Raman spectroscopy

Polymers for lithography

Polymer thin films

Kano, Kenji+

kkano@nist.gov

Dielectric relaxation of polymers

Nonlinear dielectric and conductive

spectroscopy

Organic electronics

Karim, Alamgir

alamgir.karim@nist.gov

Combinatorial and high-throughput methods

Patterning of thin-polymer blend films on

inhomogenous surfaces

Neutron & x-ray reflection and scattering

AFM and optical microscopy

Nanofilled polymer films

Nanostructured materials

Metrology for nanoscale manufacturing

Kee, Tak+

tak.kee@nist.gov

Ultrafast spectroscopy

Coherent anti-Stokes Raman scattering (CARS)

microscopy

Tissue engineering scaffolds

Confocal microscopy

Kharchenko, Semen+

semen.kharchenko@nist.gov

Stress optical properties

Birefringence

Viscoelastic properties

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

Polymer adhesion and mechanical properties

Polymer composites

Optical coherence microscopy

Kipper, Matthew+

matthew.kipper@nist.gov

Hemotactic, chemotactic response to

biomaterials

Craniofacial tissue engineering

Cell migration

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
52

Lee, Hae-Jeong+

hae-jeong.lee@nist.gov

X-ray reflectivity

Small-angle neutron scattering

Nanoimprint lithography

Structural characterization of low dielectric

constant thin films

Porosimetry of porous thin films

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

Lin, Eric K.

eric.lin@nist.gov

Polymer thin films and interfaces

Polymer photoresists for lithography

Organic electronics

Nanoimprint lithography

Small angle x-ray and neutron scattering

Statistical mechanics

X-ray and neutron reflectivity

Lin, Nancy J.

nancy.lin@nist.gov

Combinatorial screening of scaffolds

Cellular response to materials

Lin–Gibson, Sheng

sheng.lin-gibson@nist.gov

Rheology of gels and nanocomposites

Mass spectrometry of synthetic polymers

Polymer synthesis and modification

Structure and dynamics of nanocomposite

polymeric materials

Tissue engineering hydrogels

Liu, Da-Wei

da-wei.liu@nist.gov

Polymer synthesis

Thermal gravimetric analysis

Differential scanning calorimetry

Gel permeation chromatography

Infrared spectroscopy

Nuclear magnetic resonance

Markovic, Milenko*

milenko.markovic@nist.gov

Calcium phosphate chemistry

Biomineralization (normal and pathological)

Crystal growth and dissolution kinetics

Heterogeneous equilibria

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

Surface force measurements

Mei, Ying+

ying.mei@nist.gov

Polymer synthesis

Peptide synthesis

Biodegradable polymers

Biomimetic polymers

Meillon, Mathurin+

mathurin.meillon@nist.gov

Polymer rheology

Characterization of processing aids

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

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

Research Staff
53

Pathak, Jai A.+

jai.pathak@nist.gov

Rheology and linear viscoelasticity

Polymer dynamics and complex fluids

Microfluidics

Phelan, Jr., Frederick R.

frederick.phelan@nist.gov

Composites processing

Microfluidics

Viscoelastic flow modeling

Chaotic mixing

Flow in porous media

Lattice Boltzmann methods

Prabhu, Vivek M.

vivek.prabhu@nist.gov

Small-angle neutron scattering

Polyelectrolytes

Polymers for lithography

Fluorescence correlation spectroscopy

Polymer thin films

X-ray and neutron reflectivity

Quinn, Janet*

janet.quinn@nist.gov

Fractography

Dental materials and material properties

Composites

Richards, Nicola*

nicola.richards@nist.gov

Dental restorative materials

Polymer matrix composites

Rao, Ashwin B.+

ashwin@nist.gov

Polymer adsorption

Thin films gels

Fluorescence microscopy

Interfacial rheology

Ro, Hyun Wook+

hyun.ro@nist.gov

Nanoimprint lithography

Low-k dielectric thin films

X-ray reflectivity

Sambasivan, Sharadha+

sharadha@bnl.gov

Near-edge x-ray absorption fine structure

spectroscopy (NEXAFS)

Polymers for lithography

Polymer relaxation and tribology

Self assembled monolayer orientation

Catalyst surface and bulk characterization

Schumacher, Gary E.*

gary.schumacher@nist.gov

Clinical dentistry

Composites

Dentin adhesives

Simon, Carl G., Jr.

carl.simon@nist.gov

Biocompatibility

Cytotoxicity

Signaling in human platelets

Bone marrow cell lineage/trafficking

Combinatorial methods

Skrtic, Drago*

drago.skrtic@nist.gov

Bioactive amorphous calcium phosphate-based

dental materials

Smith, Jack R.

jack.smith@nist.gov

Surface science

Computational modeling

Biomaterials characterization

Snyder, Chad R.

chad.snyder@nist.gov

Polymer crystallization

WAXD and SAXS of polymeric materials

Thermal expansion measurements

Thermal analysis

Thermal management

Dielectric measurements and behavior

Ballistic resistance

Soles, Christopher L.

csoles@nist.gov

Polymer dynamics

Inelastic neutron scattering

Low-k dielectric thin films

X-ray and neutron reflectivity

Polymer thin films and lithography

Ion beam scattering

Nanoimprint lithography

Stafford, Christopher M.

chris.stafford@nist.gov

Combinatorial and high-throughput methods

Polymer thin films

Polymer adhesion

Mechanical properties of thin films

Surfaces and interfaces

Start, Paul R.+

paul.start@nist.gov

Nanocomposites

Transmission electron microscopy

Sol-gel processes

Surfactants and interfacial tension

Research Staff
54

Stephens, Jean S.

jean.stephens@nist.gov

Optical coherence microscopy

Cell/scaffold interactions

Tissue engineering

Electrospinning

Fiber morphology

Stone, Phillip A.+

philip.a.stone@nist.gov

Microfluidic devices

Dynamics of carbon nanotubes

Rheology

Sun, Limin

lsun@nist.gov

Macroporous biomaterials

Fiber-matrix interfacial shear strength

CPC composites

Taboas, Juan M.+

juan.taboas@nist.gov

Biomedical engineering

Cell and tissue mechanics

Mechanoactive bioreactors

Tissue engineering

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

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 and peroxide

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

Vogel, Brandon M.+

brandon.vogel@nist.gov

Polymer synthesis

Combinatorial methods

Drug delivery

Organic electronics

Polymer thin films

Self-assembled monolayers

Vogel, Gerald L.*

gerald.vogel@nist.gov

Dental plaque chemistry

Chemistry of calcium phosphates

Microanalytical techniques

Fluoride chemistry

Vogt, Bryan D.

bryan.vogt@nist.gov

Polymer thin film properties

X-ray and neutron reflectivity

Polymers for lithography

Quartz crystal microbalance

Ordered mesoporous materials

Organic electronics

Wallace, William E.

william.wallace@nist.gov

Mass spectrometry

Geometric data analysis methods

Wang, Francis W.

francis.wang@nist.gov

Photophysics and photochemistry of polymers

Fluorescence spectroscopy

Cure monitoring of polymerization

Tissue engineering

Wang, Xianfeng+

xianfeng.wang@nist.gov

Monte Carlo simulations

Finite element modeling

Polymer composites

Mechanical properties

Image quantitation

Weir, Michael*

michael.weir@nist.gov

Biomaterials

Tissue engineering

Degradable hydrogels

Growth factor dynamics and cellular response in

biomaterials

Wetzel, Stephanie J.

stephanie.wetzel@nist.gov

Mass spectrometry of polymers

Chemometrics

Size exclusion chromatography

Research Staff
55

Wilder, Elizabeth A.

elizabeth.wilder@nist.gov

Rheological behavior of polymer gels

Mechanical properties of polymer composites

Structure-property relationships

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

Polymer networks

Wu, Tao+

tao.wu@nist.gov

Polymer formulations

Polymer synthesis

Interfacial tension measurements

Combinatorial and high-throughput methods

Xu, Chang

chang.xu@nist.gov

Combinatorial and high-throughput methods

Polymer formulations

Surface polymerization

Xu, Hockin*

hockin.xu@nist.gov

Bone tissue engineering

Scaffold and cell interactions

Fiber and whisker composites

Zhang, Wenhua+

wezhang@nist.gov

Combinatorial and high-throughput informatics

Database structure

Laboratory automation

Polymer thin films and blends

Zhao, Hongxia (Jessica)+

jessica.zhao@nist.gov

Computed fluid dynamics

Data acquisition

Multivariate analysis

Signal processing

* Research Associate

+ Guest Scientist

Research Staff
56
57

National Institute of Standards and Technology

Materials Science and Engineering Laboratory
58

Polymers Division (854.00)