Interfacial phase transitions in molecular fluids and multicomponent mixtures

Abstract

A generalized van der Waals theory for non-uniform molecular fluids has been applied to a variety of systems, ranging from the liquid–vapour and solid–liquid interfaces of single-component fluids characterized by strongly anisotropic interactions, to the liquid–liquid interface of ternary mixtures with one amphiphilic component. These systems are characterized by a very rich interfacial structure, and under appropriate conditions exhibit wetting transitions, some of which are orientational in nature. Triple-point wetting as well as re-entrant wetting transitions also occur in some of these systems.We have calculated the density and orientational order parameter profiles in the interfacial region as well as the surface tension and adsorption for (i) the liquid–vapour and solid–liquid interfaces of simple models of nematic liquid crystals and (ii) a model of an amphiphilic surface active agent at the liquid–liquid interface of two immiscible liquids.