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Search Publications by: Jack F. Douglas (Fed)

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Displaying 51 - 75 of 355

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

Influence of Ion Solvation on the Properties of Electrolyte Solutions

April 3, 2018
Author(s)
Marat Andreev, Juan J. DePablo, Alexandros Chremos, Jack F. Douglas
It is widely appreciated that the addition of salts to water leads to significant changes in the thermodynamic and dynamic properties of these aqueous solutions, which have great significance in biology and manufacturing applications. However, no

Weak and Strong Gels and the Emergence of the Amorphous Solid State

February 23, 2018
Author(s)
Jack F. Douglas
Gels are amorphous solids whose macroscopic viscoelastic response derives from contraints in the material that serve to localize the constituent molecules or particles about their average positions in space. These contraints may either be local in nature

Topological Rigidification of Flexible Polymers in Solution

February 22, 2018
Author(s)
Jack F. Douglas, Fernando Vargas-Lara
We use molecular dynamic simulations on a coarse-grained model for flexible polymers in solution to study how molecular topology affects the intrinsic rigidity of polymeric chains. In particular, we study how polymeric "topological complexity", defined by

What Does the Tg of Thin Polymer Films Really Tell Us?

February 22, 2018
Author(s)
Wengang Zhang, Francis W. Starr, Jack F. Douglas
The disparate results for Tg shifts in ultra-thin polymer films with the same film thickness, substrate, and chemistry raises the question of whether Tg is a useful way to characterize thin films. Underlying many Tg measurements is the assumption that Tg

Valence, loop formation and universality in self-assembling patchy particles

February 7, 2018
Author(s)
Debra J. Audus, Francis W. Starr, Jack F. Douglas
Patchy particles have emerged as an attractive model for phase separation and self-assembly in globular proteins solutions, colloidal patchy particles, and molecular fluids where directional interactions are operative. In our previous work, we extensively

Energy Renormalization to Coarse-Graining of the Dynamics of a Model Glass-Forming Liquid

February 5, 2018
Author(s)
Wenjie Xia, Jake Song, Nitin Hansoge, Frederick R. Phelan Jr., Sinan Keten, Jack F. Douglas
Soft condensed matters characteristically exhibit a strong temperature dependence of relaxation properties due to glass formation, but currently no effective temperature transferable coarse- graining method exists that allows for the prediction of their

String-like Collective Motion and Diffusion in the Interfacial Region of Ice

November 20, 2017
Author(s)
Jack F. Douglas, Hao Zhang, Xuhang Tong, Xinyi Wang
We investigate the collective molecular motions and diffusion of water molecules in the mobile interfacial region of the secondary prismatic plane of hexagonal ice by molecular dynamics simulation based on the TIP4P/2005 water potential and metrologies of

Knot Energy, Complexity, and Mobility of Knotted Polymers

October 17, 2017
Author(s)
Luis F. Vargas Lara, Ahmed M. Hassan, Marc A. Mansfield, Jack F. Douglas
The Newtonian capacity C of an object is defined by the equilibrium energy, EN =1/C, of a charge distribution on a conductive object and provides a classical measure of object shape. It is well known, for example, that C is minimized for a sphere for all

Molecular Rigidity, Excess Entropy, and Enthalpy-Entropy Compensation in DNA Melting

September 24, 2017
Author(s)
Jack F. Douglas, Fernando Vargas-Lara, Francis W. Starr
Enthalpy-entropy compensation (EEC) is observed in diverse molecular binding processes of vital importance to living systems and manufacturing applications, but this widely occurring phenomenon is not well understood from a molecular physics standpoint. To