Diffusion-controlled wetting films

Abstract

The dynamics of ultra-thin wetting films has been studied experimentally under a controlled atmosphere using a dynamic ellipsometric technique. The spreading fluid was PDMS and the substrates were oxide covered silicon wafers. The situations of capillary rise up a vertical wall, and the spreading of 'nanoscopic' drops, have been compared. The development of films of near-molecular thickness, over macroscopic distances, is observed in both cases. Two diffusive processes (early and late) have been identified for the dynamics of the tips of those films. This in turn requires theoretical effort in the field of ultra-thin-film dynamics.