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Displaying 1251 - 1275 of 1923

The molecular basis of mesophase ordering in a thiophene-based copolymer

February 18, 2009
Author(s)
Dean M. DeLongchamp, Regis J. Kline, Youngsuk Jung, Eric K. Lin, Daniel A. Fischer, David J. Gundlach, Andrew Moad, Lee J. Richter, Michael F. Toney, Martin Heeney, Iain McCulloch
The carrier mobility of poly(2,5-bis(3-alkylthiophen-2-yl) thieno[3,2-b]thiophene) semiconductors can be substantially enhanced after heating through a thermotropic mesophase transition, which causes a significant improvement in thin film structural order

Adhesion at layer-by-layer surfaces in aqueous environments

February 15, 2009
Author(s)
Adam J. Nolte, Jun Y. Chung, Marlon L. Walker, Christopher M. Stafford
Adhesion between materials is often governed by the ambient environment, which can mediate or change the types of molecular interactions present at an interface. Biological interactions, for example, can be mediated by factors such as temperature, ionic

Subsurface Patterning and its Effect on Interfacial Adhesion

February 15, 2009
Author(s)
Edwin P. Chan, Christopher M. Stafford
Nature (e.g. geckos and insects) has illustrated that a patterned surface can effectively tailor the adhesion of an interface. Inspired by the amazing attachment and detachment ability of these animals, significant efforts have been put forth to understand

Ultrathin Adhesives: Confinement Effect on Modulus

February 15, 2009
Author(s)
Jessica M. Torres, Christopher Stafford, Bryan D. Vogt
In this work, we will employ this wrinkling metrology to extract the modulus of polymer thin films for a homologous series of poly(n-alkyl methacrylate)s. In particular, we take advantage of the decrease in Tg as the alkyl chain length increases for these

Predicting Failure in Mammalian Enamel

January 16, 2009
Author(s)
Brian R. Lawn, James J. Lee, Paul Constantino, Peter Lucas
Dentition is a vital element of human and animal function, yet there is little fundamental knowledge about how tooth enamel endures under stringent oral conditions. This paper describes a novel approach to the issue. Model glass dome specimens fabricated

Living Anionic Polymerization Using a Microfluidic Reactor

January 15, 2009
Author(s)
Thomas Q. Chastek, Kazunori Iida, Eric J. Amis, Michael J. Fasolka, Kathryn L. Beers, Jae H. Chun
Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 °C) and high monomer concentration (42 %, by

Impact of Polymer Chemistry on the Durability of Model Adhesives Supported on SiOx Substrates in Humid Environments Using Homologous Series of Poly(n-alkyl methacrylate)s

January 7, 2009
Author(s)
Kar T. Tan, Bryan D. Vogt, Christopher C. White, Kristen Hamilton, Nicholas Wagman, Joshua E. Goldman, Jessica M. Torres, Kristen L. Steffens, Cyril Clerici, Sushil K. Satija, Donald L. Hunston
There are many advantages that structural adhesives can offer compared to the more traditional joining methods, such as welding, bolting, mechanical fastening, etc. However, there are some issues that currently limit the wider application of adhesives. One

In-situ Adhesion Measurements Utilizing Layer-by-layer Functionalized Surfaces

January 7, 2009
Author(s)
Adam J. Nolte, Jun Y. Chung, Marlon L. Walker, Christopher Stafford
The adhesion between poly(dimethylsiloxane) (PDMS) hemispheres coated with layer-by-layer (LbL) assemblies of polyelectrolytes was investigated using Johnson, Kendall, and Roberts (JKR) contact mechanics. Measurements were performed against amine

Adhesive bonding to dentin improved by polymerizable cyclodextrin derivatives

January 5, 2009
Author(s)
Rafael L. Bowen, Gary E. Schumacher, Anthony A. Giuseppetti, Kathleen M. Flynn, Charles M. Guttman, Clifton M. Carey
Objectives. Determine bonding characteristics of a hydrophilic monomer formulation containing PCDs (Polymerizable Cyclodextrin Derivatives). The hypothesis was that a formulation containing hydrophilic cross-linking diluent comonomers and PCD molecules

Particle Motion During the Compaction of Granular Matter

December 19, 2008
Author(s)
Steven Slotterback, Masahiro Toiya, Leonard Goff, Jack F. Douglas, Wolfgang Losert
We track particle motions in a granular material subjected to compaction using a laser scattering based imaging method where compaction is achieved through thermal cycling. Particle displacements in this jammed fluid correlate strongly with rearrangments

Elastic Modulus of Faceted Aluminum Nitride Nanotubes Measured by Contact Resonance Atomic Force Microscopy

December 17, 2008
Author(s)
Gheorghe Stan, C Ciobanu, Timothy Thayer, George Wang, Randall Creighton, Premsagar P. Kavuri, Leonid A. Bendersky, Robert F. Cook
A new methodology for determining the radial elastic modulus of a one-dimensional nanostructure laid on a substrate has been developed. The methodology consists of the combination of contact resonance atomic force microscopy (AFM) with finite element

Technique for Monitoring Environmentally Induced Changes in Polymeric Sealants

December 17, 2008
Author(s)
Donald L. Hunston, Kar T. Tan, Christopher C. White
A new procedure was developed to utilize stress relaxation tests to monitor damage induced in sealant materials exposed to environmental variables and changing strains. By combining tension and compression tests, it was possible to monitor both molecular

Disordered Nanoparticle Interfaces for Defect-Tolerant Self-Assembly

November 17, 2008
Author(s)
Kevin G. Yager, Brian Berry, Kirt A. Page, Derek L. Patton, Alamgir Karim, Eric J. Amis
Self-assembly is a promising route for controlling the nanoscale structure and material properties of coatings, yet it remains difficult to control the microstructure of these systems. In particular, self-assembling materials typically have complex and
Displaying 1251 - 1275 of 1923
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