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Molecular Configurations and Solvation Forces in Confined Alkane Films

Published online by Cambridge University Press:  10 February 2011

Jee-Ching Wang
Affiliation:
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802
Kristen A. Fichthorn
Affiliation:
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802
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Abstract

We review the results of two studies [1,2] aimed at clarifying the surface forces of con fined fluids. In the first study [1], molecular-dynamics simulations are used to study the influence of chain branching on the molecular configurations of alkane films physically adsorbed on a solid surface. The symmetric n-decane molecules exhibit strong layering, while t-butyl-hexane films have a novel pillared-layered structure, in which a few randomly distributed molecules orient themselves with the t-butyl end near the surface and the alkyl tail perpendicular to the surface. These molecules are surrounded by parallel, layered molecules. In the second study [2], we outline the development of a new NPAT ensemble method, with advantages for simulating confined fluids. For confined Lennard-Jones particles simulated with the new method, clear oscillatory solvation-force profiles and step-like dependencies of the number of confined molecules on surface separation were observed. As the parallel pressure increases, the oscillations in solvation forces are enhanced and tend to become repulsive.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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