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Search Publications

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Displaying 1276 - 1300 of 1856

On the nature of asymetry of nucleation centers activity in ultrathin Co films and Co/Pt multilayers

January 14, 2008
Author(s)
Yu L. Iunin, Yury P. Kabanov, Valerian I. Nikitenko, X M. Cheng, Alexander J. Shapiro, C L. Chien, Robert D. Shull
Magnetization reversal in ultrathin Pt(10 nm)/Co(0.6 nm)/Pt(3 nm) magnetic films and Pt(10 nm)/[Co(d)/Pt(1 nm)]_n}/ Pt(2 nm) (d = 0.4, 0.6, 0.8 nm, n = 2, 4) multilayers with perpendicular anisotropy has been studied using Kerr microscopy. These materials

Model for Reversible Nanoparticle Assembly in a Polymer Matrix

January 8, 2008
Author(s)
Andrew Rahedi, Jack F. Douglas, Francis W. Starr
The clustering of nanoparticles (NP) within solutions and polymer melts depends sensitively on the strength and directionality of the NP interactions involved, as well as the molecular geometry and interactions of the dispersing fluids. Since clustering

A Device for Mechanically Folding Yarns and Woven Fabrics of Ballistic Fibers

January 7, 2008
Author(s)
Walter G. McDonough, Jae Hyun Kim, Nolan J. Brandenburg, William R. Blair, Gale A. Holmes
Abstract (2000 characters maximum - spell out acronyms the first time)An apparatus was designed and built that attaches to servo-hydraulic machines that typically perform material fatigue testing. The device was designed to systematically fold woven fabric

Multiscale modeling of point defects in strained silicon

December 31, 2007
Author(s)
Vinod Tewary, B. Yang
A multiscale Green's function method is described for modeling substitutional point defects and vacancies in strained silicon. The model seamlessly links the length scales from atomistic to macro. The model accounts for the discrete lattice effects

Certification of Standard Reference Material 1476a, a Polyethylene Resin

November 29, 2007
Author(s)
Kathleen M. Flynn, S Wetzel, William R. Blair, J R. Maurey
The melt flow rate of Standard Reference Material (SRM) 1476a Branched Polyethylene Resin was determined to be 1.23g/10 min at 190 C under a load of 2.16 kg using the ASTM Method D1238-03, method A. The average results from 30 determinations yielded a

Microdomain Ordering in Laterally Confined Block Copolymer Thin Films

November 29, 2007
Author(s)
August W. Bosse, Carlos Garcia-Cervera, Glenn Fredrickson
We examine the effects of small-scale, hexagonal, lateral confinement on microdomain ordering in $AB$ diblock copolymer thin films using self-consistent field theory (SCFT) simulations. Specifically, we examine a hexagonal confinement well with side length

Characterizing Polymer Brushes via Surface Wrinkling

November 21, 2007
Author(s)
Heqing Huang, Jun Y. Chung, Adam J. Nolte, Christopher M. Stafford
We present the application of surface wrinkling to measure the properties of polymer brush layers tethered to the surface of a deformable silicone substrate. It is demonstrated that the wavelength of the wrinkling pattern linearly increases with the length

Block Copolymer Ordering With a Spatiotemporally Inhomogeneous Mobility

November 20, 2007
Author(s)
August W. Bosse, Jack F. Douglas, Brian Berry, Ronald L. Jones, Alamgir Karim
Motivated by recent measurements of zone annealing in block copolymer films at low temperatures, we implement a spatiotemporal mobility gradient with intrinsic variations associated with dynamic heterogeneities in the saddle point relaxation of a diblock

Combinatorial Polymer Scaffold Libraries

November 1, 2007
Author(s)
Carl G. Simon Jr., J S. Stephens, Matthew Becker
We have developed a method for fabricating combinatorial libraries of porous, three-dimensional, salt-leached, polymer scaffolds that can be used for screening the effect of scaffold properties on cell response. Syringe pumps, tubing and a static mixer are

Critical Role of Side-Chain Attachment Density on the Order and Device Performance of Polythiophenes

October 30, 2007
Author(s)
Regis J. Kline, Dean DeLongchamp, Daniel A. Fischer, Eric K. Lin, Lee J. Richter, Michael L. Chabinyc, Martin Heeney, Iain McCulloch
High performance, solution processable semiconductors are critical to the realization of low cost, large area electronics. We show that a signature molecular packing motif - side-chain interdigitation - correlates to high performance for a large and

The Molecular Origin of Enhanced Toughness in Double-Network Hydrogels

October 22, 2007
Author(s)
Taiki Tominaga, Vijay Tirumala, Eric K. Lin, Jian P. Gong, Hidemitsu Furukawa, Yoshihito Osada, Wen-Li Wu
The long-standing pursuit of a synthetic equivalent to tissue cartilage has seen significant new activity with the development of a new materials strategy: double-network hydrogels (DN-gels) prepared from a combination of an anionic polyelectrolyte and a

Dynamics of Confined Polymer Films Measured via Thermal Wrinkling

October 19, 2007
Author(s)
Kirt A. Page, Derek L. Patton, Rui Huang, Christopher Stafford
In the past several years there have been a number of advances in the understanding of the physics of polymer thin films. However, there still remains a wide range of opportunities to further this understanding through the development of measurement tools

Measurement of Reactivity Ratios in Surface-Initiated Copolymerization

August 21, 2007
Author(s)
Derek L. Patton, Kirt A. Page, Chang Xu, Kirsten Genson, Michael J. Fasolka, Kathryn L. Beers
This work describes a new approach to measure monomer reactivity ratios from surface-initiated copolymerizations using x-ray photoelectron spectroscopy. Styrene/methyl methacrylate statistical copolymer brushes were prepared from various monomer feeds by

Relaxation Behavior of Polymer Structures Fabricated by Nanoimprint Lithography

August 14, 2007
Author(s)
Yifu Ding, Hyun Wook Ro, Thomas A. Germer, Jack F. Douglas, Brian C. Okerberg, Alamgir Karim, Christopher L. Soles
We study the decay of the imprinted polystyrene (PS) patterns under thermal annealing using light diffraction. The first order diffraction intensity from the imprinted gratings was measured as a function of annealing time. Local intensity maximum is

Microfluidic Dynamic Light Scattering Used for High Throughput Measurements

July 10, 2007
Author(s)
Thomas Q. Chastek, Kathryn L. Beers, Eric J. Amis
When diluted in some solvents, surfactants and block copolymers self-assemble into micelles or vesicles of about 10-100 nm in size. There is a great deal of interest in micelles and vesicles because they are widely used in the formulations industry, and

Characterization of the Potential Energy Landscape in an Antiplasticized Polymer

July 6, 2007
Author(s)
Robert A. Riggleman, Jack F. Douglas, J J. de Pablo
Transition state searches have been performed on model coarse-grained polymer systems, and the results compared to those of an antiplasticized polymer system, which have been previously shown to be fragile and strong glass-forming systems, respectively. It

Tuning Polymer Melt Fragility With Antiplasticizer Additives

June 19, 2007
Author(s)
Robert A. Riggleman, Jack F. Douglas, J J. de Pablo
A polymer-diluent model exhibiting antiplasticization has beendeveloped and characterized by molecular dynamics simulations. Antiplasticizer molecules are shown to decrease the glass transition temperature Tg, but to increase the elastic moduli of the
Displaying 1276 - 1300 of 1856