MACROSCOPIC THEORY OF WETTING IN A WEDGE

Wetting in a ("concave") wedge, or corner, is considered from a macroscopic point of view. Combination with basic thermodynamics of the classic equations due to Laplace and Young yields, surprisingly, a number of interesting results in this context. The wetting transition is shifted to lower temperatures and is no longer confined to the coexistence line, but extends a finite distance into the gas phase. Regardless of the nature of the wetting transition on a flat substrate, the wetting transition in a wedge is continuous, sharpening to a first-order transition as coexistence is reached. The extent of the region in which macroscopic arguments apply is discussed, and is found to depend on the detailed nature of the wetting transition on a flat substrate. Finally, we speculate that wedge wetting might open up new possibilities for observing phenomena connected with the prewetting line.