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Search Publications by: Jack F. Douglas (Fed)

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Displaying 101 - 125 of 355

Self-Assembly of Polymer-Grafted Nanoparticles in Solvent-free Conditions

October 31, 2016
Author(s)
Alexandros Chremos, Jack F. Douglas
The grafting of polymer chains onto the surface of spherical nanoparticles leads to a hybrid type of fluid that exhibits properties of both particle suspensions and melts of star polymers – these properties being controlled by the relative dimensions of

Influence of Pressure on Glass Formation in a Simulated Polymer Melt

October 18, 2016
Author(s)
Jack F. Douglas, Wensheng Xu, Karl Freed
We investigate the thermodynamic and dynamic properties of a model unentangled glass-forming polymer melt over a wide range of pressures (P) and temperatures (T) using molecular dynamics simulation. We show that the T dependence of the reduced thermal

Supramolecular Self-assembly of a Novel Hydrogelator: Characterization of Fiber Morphology and Formation and Thermal-Reversible Gelation

October 8, 2016
Author(s)
Jack F. Douglas, Yuan Gao Yuan Gao, Ryan C. Nieuwendaal, Emilios Dimitriadis, Boualem Hammouda, Bing Xu, Ferenc Horkay
Hydrogels are of intense recent interest in connection with biomedical applications ranging from 3-D cell cultures and stem cell differentiation to regenerative medicine, controlled drug delivery and tissue engineering. This prototypical form of soft

The Glass Transition of a Single Macromolecule

September 21, 2016
Author(s)
Jack F. Douglas, David Simmons, Weston L. Merling, Jack Mileski
The glass transition of a single macromolecule in isolation is relevant to the dynamics of systems including dilute solutions of synthetic polymers and biological macromolecules such as proteins. Here we employ molecular dynamics simulation to show that a

Conformational Nature of DNA–Grafted Chains on Spherical Gold Nanoparticles

September 10, 2016
Author(s)
Jack F. Douglas, Fernando Vargas-Lara
We investigate the conformational state of a simple, coarse–grained molecular model for single–stranded DNA chains (ss-DNA) grafted onto spherical symmetric gold nanoparticles (NPs) and of the grafted layer as a whole by molecular dynamic simulations. In

Giant surface conductivity enhancement in a carbon nanotube composite by ultraviolet light exposure

July 29, 2016
Author(s)
Christian J. Long, Nathan D. Orloff, Kevin A. Twedt, Thomas F. Lam, Luis Fernando Vargas Lara, Minhua Zhao, Bharath NMN Natarajan, Keana C. Scott, Eric Marksz, Tinh Nguyen, Jack F. Douglas, Jabez J. McClelland, Edward J. Garboczi, Jan Obrzut, James A. Liddle
Carbon nanotube composites are lightweight, multifunctional materials with readily adjustable mechanical and electrical properties—relevant to the aerospace, automotive, and sporting goods industries as high-performance building materials. Here, we combine

Evolution of Dendrimer Conformational Structure with Generation Number

June 20, 2016
Author(s)
Beatriz A. Pazmino, Jack F. Douglas
We simulate the conformational structure of a coarse-grained model of dendrimer molecules in good solvent as a function of generation number G and find that they evolve through a substantially more complex structures than regular star polymer with

Hydrodynamic Radius Fluctuations in Model DNA-Grafted Nanoparticles

June 16, 2016
Author(s)
Luis Fernando Vargas Lara, Francis W. Starr, Jack F. Douglas
We utilize molecular dynamics simulations (MD) and the path-integration program ZENO to quantify hydrodynamic radius (Rh) fluctuations of spherical symmetric gold nanoparticles (NPs) decorated with single-stranded DNA chains (ssDNA). In particular, we

Pattern-Directed Phase Separation of Polymer-Grafted Nanoparticles in a Homopolymer Matrix

May 12, 2016
Author(s)
Ren Zhang, Bongjoon Lee, Michael R. Bockstaller, Sanat K. Kumar, Christopher Stafford, Jack F. Douglas, Dharmaraj Raghavan, Alamgir Karim
The controlled organization of nanoparticle (NP) constituents into superstructures of well- defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We

Bottom Up Approaches to Improved Polyolefin Measurements

February 4, 2016
Author(s)
Sara Orski, Thomas W. Rosch, Anthony Kotula, Richard J. Sheridan, Frederick R. Phelan Jr., Kalman Migler, Chad R. Snyder, Luis F. Vargas Lara, Jack F. Douglas, Kathryn L. Beers
As a class of materials, polyolefins remain the largest production volume polymer in the world, as well as a highly desirable medium from which to engineer high performance and advanced properties for new applications. After decades of research, there are

Polymer Glass-Formation in Variable Dimension

January 14, 2016
Author(s)
Jack F. Douglas, Freed Karl, Wensheng Xu
We explore the nature of glass-formation in variable spatial dimensionality (d) based on the generalized entropy theory, a synthesis of the Adam-Gibbs model with direct computation of the configurational entropy of polymer fluids using an established