Wetting at triple junctions and the universality of wetting near critical points

Triple junctions (i.e., boundaries where three systems meet) constitute an interesting geometry for wetting phenomena. We study an Ising model of a triple junction, using Landau theory and scaling arguments. Various phenomena are predicted, from the familiar critical-point wetting to the opposite, critical-point dewetting. The latter prevails when fluctuations are taken into account. A comparison of wetting at triple junctions with wetting at walls and wetting at grain boundaries indicates an interesting universality. Critical-point wetting occurs whenever the surface displays (spontaneous or imposed) order at the bulk critical point.