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Publications

Search Publications by

Jack F. Douglas (Fed)

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Displaying 26 - 50 of 344

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

A Comparison Between The Solution Properties of Knotted Ring and Star Polymers

October 31, 2018
Author(s)
Luis F. Vargas Lara, Beatriz Pazmino, Jack F. Douglas
We computationally investigate the solution properties of knotted flexible ring and star polymers by combining molecular dynamics simulation (MD) and path-integral calculations. In particular, we consider knotted rings having a minimal crossing number mc

Complex coacervation in polyelectrolytes from a coarse-grained model

August 22, 2018
Author(s)
Jack F. Douglas, Marat Andreev, Juan J. DePablo, Vivek Prabhu, Matthew Tirrell
Polyelectrolyte coacervation refers to the formation of distinct liquid phases that arise when polyelectrolytes are mixed under appropriate polymer and salt concentrations. Molecular-level studies of complex polyelectrolyte coacervation have been limited

Complex coacervation in polyelectrolytes from a coarse-grained model

August 22, 2018
Author(s)
Vivek M. Prabhu, Marat Andreev, Jian Qin, Matthew Tirrell, Juan J. de Pablo, Jack F. Douglas
Polyelectrolyte coacervation refers to the formation of distinct liquid phases that arise when polyelectrolytes of opposite charge are mixed under appropriate polymer and salt concentrations. Molecular-level studies of complex polyelectrolyte coacervation

Competitive solvation effects in polyelectrolyte solutions

August 1, 2018
Author(s)
Alexandros Chremos, Jack F. Douglas
An understanding of the solution properties and phase behavior of natural and synthetic polyelectrolytes requires an understanding of the competitive association of water (“hydration”) and ion association to the polymer backbone and the consequences of

Polyelectrolyte association and solvation

July 10, 2018
Author(s)
Alexandros Chremos, Jack F. Douglas
There has been significant interest in the tendency of highly charged particles having the same charge to form dynamic clusters in solution, but an accepted theoretical framework that can account for this ubiquitous phenomenon has been slow to develop. The

Structure and Dynamics of a Graphene Melt

May 22, 2018
Author(s)
Jack F. Douglas, Sinan Keten, Fernando Vargas-Lara, Wenjie Xia
We show by molecular dynamics simulation that bulk materials composed of graphene nanosheets exhibit fluid-like properties similar to linear polymer melts at elevated temperatures and that these materials transform into a glassy or “foam” state at low

Energy Renormalization Method for the Coarse-Graining of Polymer Viscoelasticity

May 10, 2018
Author(s)
Jake Song, David D. Hsu, Kenneth R. Shull, Frederick R. Phelan Jr., Jack F. Douglas, Wenjie Xia, Sinan Keten
Developing time and temperature transferable coarse-grained (CG) models is essential for the computational prediction and design of polymeric glass-forming materials, but this goal has remained elusive. The dynamics of CG models are often greatly altered