The liquid-vapour interface of simple models of nematic liquid crystals

Abstract

We have applied a recently developed statistical mechanical theory for the interfacial properties of strongly anisotropic fluids to the liquid-vapour interface of a model nematic at the triple point temperature T _tr, i.e. at the nematic-isotropic transition under conditions of saturated vapour pressure. We have investigated the structure of the interfacial region, and in particular we have studied the dependence of the orientational order parameter profiles on the details of the intermolecular potential characterizing the system. We find that both parallel and perpendicular orientations of the molecules at the nematic free surface can be obtained, depending on the sign of one of the parameters that specify the interactions, in qualitative agreement with experimental results.

The surface tension of the nematic-vapour interface is found to exhibit a type of reentrant wetting behaviour at T _tr which has so far not been seen experimentally.