A SIMPLE-MODEL OF WETTING, PREWETTING, AND LAYERING TRANSITIONS OF STRUCTURED LIQUIDS

A simple phenomenological model is proposed of wetting a substrate pos sessing a van der Waals long-range attraction by a liquid film which h as the damped oscillatory surface density profile. At the liquid-vapor coexistence along the coexistence line, we predict successive transit ions from incomplete wetting to no wetting, then to the complete wetti ng, as well as the usual wetting transition from incomplete wetting to complete wetting. However, at undersaturated pressures when the struc ture of the liquid becomes important, we predict not only the prewetti ng but also the layering transition. Simple criteria of those transiti ons using macroscopic and structural quantities are presented. The ter mination of the layering transition is explained by the capillary fluc tuation. (C) 1998 Academic Press.