title: Monte Carlo Simulations of an Isolated n-Octadecane Chain Solvated in Water-Acetonitrile Mixtures.
abstract: To investigate conformational properties of an isolated n-octadecane chain solvated in water-acetonitrile mixtures, configurational-bias Monte Carlo simulations in the isobaric-isothermal ensemble were performed at T = 323 K and p = 10 atm. The united-atom version of the transferable potentials for phase equilibria force field was used to represent n-octadecane and acetonitrile, and the TIP-4P model was used for water. In all four environments (neat water, 33 and 67 mole percent acetonitrile, and neat acetonitrile), similar conformational distributions are observed as in a previous study for water-methanol solvent mixtures; that is, the n-octadecane chain is found to predominantly adopt extended but not all-trans conformations, and only a small fraction of more collapsed conformations is observed for aqueous hydration, water-rich solvent environments. Analysis of the local solvation structures in the water-acetonitrile mixtures shows an enrichment of the acetonitrile molecules near the methylene and methyl segments of the n-octadecane chain. However, upon increasing the concentration of acetonitrile, the enhancement of acetonitrile and the depletion of water is more pronounced than for water-methanol mixtures because of the weaker interactions between acetonitrile and water.
authors.affiliation: Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, and Theoretical Separation Science Laboratory, Rohm and Haas Company, 727 Norristown Road, P.O. Box 0904, Spring House, Pennsylvania 19477.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.affiliation: Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, and Theoretical Separation Science Laboratory, Rohm and Haas Company, 727 Norristown Road, P.O. Box 0904, Spring House, Pennsylvania 19477.
authors.forename: J Ilja
authors.initials: JI
authors.lastname: Siepmann
authors.affiliation: Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, and Theoretical Separation Science Laboratory, Rohm and Haas Company, 727 Norristown Road, P.O. Box 0904, Spring House, Pennsylvania 19477.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Schure