Wetting on Random Roughness: the Ubiquity of Wenzel Prewetting

TL;DR

This paper demonstrates that Wenzel prewetting is a common phenomenon on rough surfaces, occurring under mild conditions and involving a sudden increase in liquid adsorption at a specific contact angle.

Contribution

It extends the understanding of wetting transitions by showing the ubiquity of Wenzel prewetting on randomly rough surfaces derived from Gaussian processes.

Findings

Wenzel prewetting occurs under mild conditions on random rough surfaces.

A prewetting transition involves a jump in adsorbed liquid volume.

The transition coincides with the Wenzel angle on rough surfaces.

Abstract

The wetting properties of solid substrates with macroscopic random roughness are considered as a function of the microscopic contact angle of the wetting liquid and its partial pressure in the surrounding gas phase. It is shown that Wenzel prewetting, which has been recently predicted for a rather wide class of roughness profiles derived from Gaussian random processes by a general distortion procedure, should in fact be ubiquitous and prevail under even much milder conditions. The well-known transition occurring at Wenzel's angle is accompanied by a prewetting transition, at which a jump in the adsorbed liquid volume occurs. This should be present on most surfaces bearing homogeneous, isotropic random roughness.