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Search Publications by: Jack F. Douglas (Fed)

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Displaying 126 - 150 of 355

Cosolvency and cononsolvency explained in terms of a Flory-Huggins type theory

October 7, 2015
Author(s)
Jack F. Douglas, Jacek Dudowicz, Freed Karl
Standard classic Flory-Huggins (FH) theory is employed to describe the enigmatic cosolvency and co-nonsolvency phenomena for systems of polymers dissolved in mixed solvents. In particular, phase boundaries (spinodals) are calculated for solutions of

When does a branched polymer becomes a particle?

September 17, 2015
Author(s)
Alexandros Chremos, Jack F. Douglas
Melts with topologically distinct molecular structures are investigated by molecular dynamics simulation. We determine the mean polymer size and shape, and glass transition temperature for each molecular topology. Both in terms of structure and dynamics

The Osmotic Virial Repersentation of the Free Energy of Polymer Mixing

September 14, 2015
Author(s)
Jack F. Douglas, August W. Bosse
In this Letter we derive a new representation of the free energy of polymer mixing. We begin with a Flory-Huggins-like free energy of mixing, and assume that the excess free energy of mixing exhibits an arbitrary dependence on the blend composition that

Direct Immersion Annealing of Thin Block Copolymer Films

September 9, 2015
Author(s)
Jack F. Douglas, Alamgir Karim, Arvind Arvind Modi1, Sarang Bhaway, Bryan D. Vogt, Abdullah Al-Enizi, Ahmed Elzatahry, Ashutosh Sharma
We demonstrate that direct immersion annealing (DIA) greatly enhances the rate at which block copolymer (BCP) films order into stable morphologies when the BCP films are immersed in carefully selected mixtures of good and marginal solvents that can impart

Dimensional Reduction of Duplex DNA Under Nanofluidic Slit Confinement

August 19, 2015
Author(s)
Luis Fernando Vargas Lara, Jack F. Douglas, Samuel M. Stavis, Elizabeth A. Strychalski, Jon C. Geist, Brian J. Nablo
There has been much recent interest in the dimensional properties of duplex DNA under nanoscale confinement conditions as a problem of fundamental interest in both technological and biological fields. This has led to a series of measurements by

A Unifying Framework to Quantify the Effects of Boundary Stiffness, Polymer-Substrate Interactions and Substrate Roughness on the Dynamics of Thin Supported Polymer Films

June 21, 2015
Author(s)
Jack F. Douglas, Paul Hanakata, Francis W. Starr, Beatriz Betancourt
Changes in the dynamics of supported polymer films in comparison to bulk materials involve a complex convolution of effects, such as boundary thermodynamic interactions, boundary roughness and compliance, in addition to finite film thickness. We consider

Confronting the Complexity of Commercial Carbon Nanotube Materials

May 13, 2015
Author(s)
Luis Fernando Vargas Lara, Jack F. Douglas
The morphology of commercially available carbon nanotube materials is often much more complex than the term “carbon nanotube” (CNT) would imply. Commercial CNT materials are typically composed of roughly spherical CNT domains having a highly ramified

Interplay of particle shape and suspension properties: a study of cube-like particles

March 20, 2015
Author(s)
Debra J. Audus, Ahmed M. Hassan, Edward J. Garboczi, Jack F. Douglas
With advances in anisotropic particle synthesis, particle shape is now a feasible parameter for tuning suspension properties. However, there is a need to determine how these newly synthesized particles affect suspension properties and a need to solve the

Critical Examination of the Colloidal Particle Model of Globular Proteins

February 3, 2015
Author(s)
Prasad S. Sarangapani, Steven D Hudson, Ronald L. Jones, Jack F. Douglas, Jai A. Pathak
Recent studies of globular protein solutions have uniformly adopted a colloidal view of proteins as particles, a perspective that neglects the polymeric primary structure of these biological macromolecules, their intrinsic flexibility and their ability to

Advances in the generalized entropy theory of glass-formation in polymer melts

December 21, 2014
Author(s)
Jack F. Douglas, J Dudowicz, Karl Freed
The generalized entropy theory (GET) of polymeric glass-forming liquids is reformulated in a simpler and more natural formalism than our previous version of this theory. This new theory is then applied to survey essential trends in the dependence of the

Prediction and Validation of Diffusion Coefficients in a Model Drug Delivery System Using Microsecond Atomistic Molecular Dynamics Simulation and Vapor Sorption Analysis

October 21, 2014
Author(s)
Christopher Forrey, D M. Saylor, Joshua S. Silverstein, Jack F. Douglas, Eric Davis, Yossef A. Elabd
Diffusion of small to medium sized molecules in polymeric medical device materials underlies a broad range of public health concerns related to unintended leaching from or uptake into implantable medical devices. Knowledge of diffusion rates is thus

High-speed, high-purity separation of gold nanoparticle-DNA origami constructs using centrifugation

July 23, 2014
Author(s)
Seung H. Ko, Luis F. Vargas Lara, Paul Patrone, Samuel Stavis, Francis W. Starr, Jack F. Douglas, James Alexander Liddle
DNA origami is a powerful platform for assembling gold nanoparticle constructs, an important class of nanostructure with numerous applications. Such constructs are assembled by the association of complementary DNA oligomers. These association reactions

Rippling Instability of Supported Polymer Nanolines

February 21, 2012
Author(s)
Vijaya R. Tirumala, Christopher M. Stafford, Leonidas E. Ocola, Jack F. Douglas, L. Mahadevan
The swelling response of polymer line gratings supported on a rigid substrate has direct implications on their mechanical stability during pattern transfer in nanofabrication. The polymer lines, when swollen in a good solvent, undergo a rippling

Using Block Copolymer Self-Assembly to Imprint the Crystallization of Polymer Dendrites

August 10, 2011
Author(s)
Sangcheol Kim, Alamgir Karim, Jack F. Douglas, Christopher L. Soles, R M. Briber
We utilize the self-assembly of cylinder-forming block copolymer (BCP) films to create templates for dendritic polymer crystallization patterns. This templating was achieved by simply spin-casting thin films from a solution containing both the BCP

Flexure-induced structural and electronic changes in polymer supported membranes of length purified single-wall carbon nanotubes

February 22, 2011
Author(s)
John M. Harris, Ganjigunte R. Iyer, Daneesh O. Simien, Jeffrey Fagan, JiYeon Huh, Jun Y. Chung, Steven Hudson, Jan Obrzut, Jack F. Douglas, Christopher Stafford, Erik K. Hobbie
Thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially compressed by depositing them on prestretched polymer substrates. Upon release of the strain, the topography, microstructure and conductivity of the films are