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Search Publications by: Jack F. Douglas (Fed)

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Displaying 26 - 50 of 355

Dynamic Heterogeneity and Collective Motion in Star Polymer Melts

February 4, 2020
Author(s)
Jack F. Douglas, Jinpeng Fan, Hamed Emamy, Francis W. Starr, Alexandros Chremos
While glass formation of linear chain polymers has been widely explored, comparatively little is known about glass formation in star polymer melts. We study the segmental dynamics of star polymers via molecular dynamics simulations and contrast the

Influence of Polymer Topology on Crystallization in Thin Films

January 22, 2020
Author(s)
Jack F. Douglas, Andrea Giuntoli, Alexandros Chremos
We investigate how varying molecular topology of polymers influences crystallization in thin polymer films. In particular, we simulate linear and star polymers having a progressively increasing number of arms (f ≤ 16) for fixed molecular mass of polymer

Lattice theory for binding of linear polymers to a solid substrate from polymer melts: II. Influence of van der Waals interactions and chain semi?exibility on molecular binding and adsorption

September 30, 2019
Author(s)
Jack F. Douglas, Jacek Dudowicz, Karl Freed
The Polymeric Langmuir Theory (PLT), developed in Paper I, is employed to investigate the influence of van der Waals interactions and chain rigidity on the thermodynamics of the reversible molecular binding to interfaces in one component polymer fluids

The Interfacial Zone in Thin Polymer Films and Around Nanoparticles in Polymer Nanocomposites

September 26, 2019
Author(s)
Jack F. Douglas, Wengang Zhang, Hamed Emamy, Fernando Vargas-Lara, Beatriz Betancourt, Francis W. Starr
We perform coarse-grained simulations of model unentangled polymer materials to quantify the range over which interfaces alter the structure and dynamics in the vicinity of the interface. We study both model polymer-nanoparticle (NP) composites with

The Interfacial Zone Around Nanoparticles in Polymer Nanocomposites

September 2, 2019
Author(s)
Jack F. Douglas, Beatriz Betancourt, Fernando Vargas-Lara, Francis W. Starr, Wengang Zhang
We perform coarse-grained simulations of model nanoparticles having a diameter on the order of 10 nm in an unentangled polymer matrix in the limit of low nanoparticle concentration to understand how the presence of nanoparticles alter the segmental

Three-state structural heterogeneity in a model two dimensional liquid

August 3, 2019
Author(s)
Jack F. Douglas, Tamoghna Das
Three structural populations with distinct average mobility are identi ed within an equilibrium two-dimensional Lennard-Jones uid simulated via molecular dynamics at a constant temperature and varying density. Quantifying the structure of the immediate

Analysis of Different Computational Techniques for Calculating the Polarizability Tensors of Stem Cells with Realistic Three-Dimensional Morphologies

July 15, 2019
Author(s)
Jack F. Douglas, Beatriz Betancourt, Somen Baidya, Ahmed M. Hassan, Waleed Al-Shaikhli, Edward J. Garboczi
In living systems, it is frequently stated that form follows function by virtue of evolutionary pressures on organism development, but in the study of how functions emerge at the cellular level, function often follows form. We study this chicken versus egg

Superionic UO2: A Model Anharmonic Crystalline Material

May 7, 2019
Author(s)
Jack F. Douglas, Hao Zhang, Xinyi Wang, Alexandros Chremos
Crystalline materials at elevated temperatures and pressures can exhibit properties more reminiscent of simple liquids than ideal crystalline materials, an attribute making these materials useful in diverse applications. Superionic crystalline materials

Energy Renormalization for Coarse-Graining Polymers Having Different Segmental Structures

April 19, 2019
Author(s)
Jack F. Douglas, Wenjie Xia, Nitin K. Hansoge, Wen-Sheng Xu, Sinan Keten, Frederick R. Phelan Jr.
We apply the recently developed energy renormalization (ER) method to coarse-graining representative polymer melts having a relatively low, intermediate and high degree of glass fragility, i.e., polybutadiene, polystyrene, and polycarbonate, respectively

Influence of Knot Complexity on Glass-Formation in Ring Polymer Melts

March 13, 2019
Author(s)
Luis F. Vargas Lara, Beatriz Pazmino, Jack F. Douglas
We perform molecular dynamic simulations on a coarse-grained polymer melt to study the dynamics of glass-formation in ring polymer melts of variable knot complexity. After generating melts of non-concatenated polymeric rings having a range of minimum

Hidden Hyperuniformity in Bottlebrush Polymer Melts

December 21, 2018
Author(s)
Alexandros Chremos, Jack F. Douglas
We show that the backbone chains of bottlebrush polymer melts exhibit a hidden hyperuniform packing over a wide temperature range above glass transition temperature. These findings open a venue for a practical design of hyperuniform polymeric materials for

Cooperative Dynamics in a Model DPPC Membrane Arise from Membrane Layer Interactions

December 19, 2018
Author(s)
Kiley Kennedy, Neha Shafique, Jack F. Douglas, Francis W. Starr
The dynamics of model membranes can be highly heterogeneous, especially in more ordered dense phases. Experimentally, monolayers are often studied as a model system to infer the properties of membranes. To better understand the origins of this

Hierarchically Patterned Elastomeric and Thermoplastic Polymer Films through Nanoimprinting and Ultraviolet Light Exposure

November 13, 2018
Author(s)
Jack F. Douglas, Ying Chen, Manish Kulkarni, Allan Marshall, Alamgir Karim, ZiLu Wang, Xiaoteng Wang, Abdullah Al-Enizi, Ahmed Elzatahry, Andrey V. Dobrynin
We develop a simple and generally applicable method to fabricate hierarchical interfacial patterns in elastomer and thermoplastic polymer films through a combination of nanoimprinting and UVO microlithography. Using this method, tunable and hierarchically

Tuning the Relaxation of Nano-Patterned Polymer Films with Polymer-Grafted Nanoparticles: Observation of Entropy-Enthalpy Compensation

November 6, 2018
Author(s)
Sonal Bhadauriya, Xiaoteng Wang, Jack F. Douglas, Praveen Pitliya, Jianan Zhang, Dharmaraj Raghavan, Michael R. Bockstaller, Christopher Stafford, Alamgir Karim
Polymer films provide a versatile "plastic" material in which complex functional relief patterns can be imprinted with a resolution down to tens of nanometers. However, the utility of such patterned materials is limited by the tendency of imprinted

Tuning the Relaxation of Nanopatterned Polymer Films with Polymer-Grafted Nanoparticles: Observation of Entropy–Enthalpy Compensation

November 6, 2018
Author(s)
Jack F. Douglas, Xiaoteng Wang, Sonal Bhadauriya, Ren Zhang, Praveen Pitliya, Dharmaraj Raghavan, Alamgir Karim
We show that the previously observed polymeric clustering of nanoparticles (NPs) with grafted chains within polymer matrices can be pattern-directed by nanoimprinting ultrathin nanocomposite films so that the NPs segregate to thicker film regions where