Pre-dewetting transition on a hydrophobic wall: Statics and dynamics

TL;DR

This paper predicts and analyzes a pre-dewetting phase transition on hydrophobic walls, detailing its static phase diagram and dynamic behavior during decompression and compression, using theoretical models and numerical calculations.

Contribution

It introduces a theoretical prediction of the pre-dewetting transition, combining numerical and analytical methods to explore static and dynamic aspects on hydrophobic surfaces.

Findings

Pre-dewetting transition line starts from the coexistence curve.

Layer thickness changes during decompression and compression.

Latent heat convection affects temperature near the film.

Abstract

For one-component fluids, we predict a pre-dewetting phase transition between a thin and thick low-density layer in liquid on a wall repelling the fluid. This is the case of a hydrophobic wall for water. A pre-dewetting line starts from the coexistence curve and ends at a surface critical point in the phase diagram. We calculate this line numerically using the van der Waals model and analytically using the free energy expansion up to the quartic order. We also examine the pre-dewetting dynamics of a layer created on a hydrophobic spot on a heterogeneous wall. It is from a thin to thick layer during decompression and from a thick to thin layer during compression. Upon the transition, a liquid region above the film is cooled for decompression and heated for compression due to latent heat convection and a small pressure pulse is emitted from the film into the liquid.