Influence of wetting on phase equilibria: A novel mechanism for critical-point shifts in films

A fluid confined between two parallel walls that exert different (competitive) surface fields may exhibit phase equilibria strikingly different from those found for equal fields. Macroscopic arguments and an explicit mean-field analysis predict that if the fields are such that the fluid wets one wall and dries the other (above a certain critical wetting transition temperature Tw) coexistence of two phases can only occur, for finite wall separation L, when TTc,L, where the critical temperature Tc,L lies below Tw. A scaling Ansatz suggests where βₛ is the exponent that describes the growth of the wetting layer.