Molecular dynamics study of hydrophobic aggregation in water/methane/methanol systems

Abstract

Computer simulations of an initially disordered molecular fluid composed of water and methane exhibit a phase-separation into a cylindrical core of methane molecules surrounded by an aqueous phase. A water/methane/methanol system also supports two phases, with only a weak preferential solvation of the methyl part of methanol into the hydrocarbon-core region. Increasing the pressure decreases the size of the hydrocarbon cylinder but increases the solvation of methanol into the methane phase. At sufficiently high pressures, the phase separation is inhibited by a formation of small methane clusters into water cavities or clathrates.