Wetting, dewetting, and reentrant wetting in Landau theory and lattice mean-field theory

Complete wetting (or drying) of a substrate is generally expected and often observed when the adsorbate is close to its critical point: critical-point wetting as conjectured by Cahn. Exceptions to this behavior have been found in experiments and theories involving competing forces of short and long range: persistent partial wetting. More recently, another mechanism for persistent partial wetting has been discovered in the Landau theory with only short-range forces. Furthermore, the precise opposite of critical point wetting has been demonstrated as a possibility in that theory: critical-point dewetting. We study this phenomenon and show that it is not an artifact of the Landau theory but a feature displayed by the mean-field theory for Ising lattice models as well.