Personal & Home Care, Food & Agriculture – Page 42

DNA Translocation Across Protein Channels: How does a polymer worm through a hole?

Muthukumar M., University of Massachusetts, US

Conformational entropy of a polymer is reduced when the polymer confronts a narrow path. The reduction in entropy and the consequent free energy barriers control the polymer's translocation through narrow channels. Recent results on our [...]

Development of Thermodynamic Methods for the study of Nanopores

Paul R., Paddison S.J., University of Calgary, CA

A statistical mechanical formalism is presented for the calculation of the thermodynamic properties of the water in nanopores of polymer electrolytes, with particular emphasis on the polarization. We describe a method that exploits the variational [...]

Molecular Modeling of Proton Conduction in Polymer Electrolyte Membranes of Nafion® Type

Paddison S.J., Eikerling M., Zawodzinski_Jr. T.A., Pratt L.R., Los Alamos National Laboratory, US

Molecular mechanisms of proton conduction in polymer electrolyte membranes are addressed by ab initio molecular dynamics calculations, utilizing the VASP program, on the model system trifluoromethane sulfonic acid monohydrate solid. After establishing that the experimental [...]

Soft Condensed Matter

Large-scale Simulations of Adhesion in Dense Polymer Melts

Sides S.W., Grest G.S., Stevens M.J., Sandia National Laboratories, US

We study adhesion between a polymer melt and substrate due to tethered chains on the substrate surface. We have performed extensive molecular dynamics simulations to study the effect of tethered chain density (S), tethered chain [...]

Modeling and Mass-Distance Scaling of a Nanometer Starburst Polymer

Rothschild W.G., Wayne State University, US

We report numerical scaling of cumulative mass with intramolecular distance of a model of one of the four segments of the hyperbranched poly(propylene!imine)-dendr-DAB(CN)64 molecule. Assuming prevalent repulsive link!link forces gives a power law relation with [...]

Illustrative Modeling Studies on Elastomers and Rubberlike Elasticity

Mark J.E., The University of Cincinnati, US

Examples are given to illustrate the use of computer modeling to elucidate the structures of elastomeric polymer networks, and to provide guidance on controlling these structures to maximize mechanical properties. The first example involves simulations [...]

Colloidal Aggregation in the Presence of Gravity

Gonzalez A.E., Universidad Nacional Autonoma de Mexico, MX

A computational model for colloidal aggregation is presented that considers the Brownian motion, the sedimentation and the deposition experienced by the colloidal particles and clusters. Among the results, for intermediate strengths of the downward gravitational [...]

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