First-order layering and critical wetting transitions in non-additive hard sphere mixtures

TL;DR

This paper uses density functional theory to study entropic wetting phenomena in asymmetric non-additive hard sphere mixtures, revealing first-order layering and critical wetting transitions near coexistence.

Contribution

It introduces a theoretical analysis of wetting transitions in non-additive hard sphere mixtures, highlighting the role of non-additivity and asymmetry in adsorption behavior.

Findings

Identification of first-order layering transitions near coexistence

Observation of critical wetting transition with continuous film growth

Analysis of preferential adsorption due to species size differences

Abstract

Using fundamental-measure density functional theory we investigate entropic wetting in an asymmetric binary mixture of hard spheres with positive non-additivity. We consider a general planar hard wall, where preferential adsorption is induced by a difference in closest approach of the different species and the wall. Close to bulk fluid-fluid coexistence the phase rich in the minority component adsorbs either through a series of first-order layering transitions, where an increasing number of liquid layers adsorbs sequentially, or via a critical wetting transition, where a thick film grows continuously.