A microscopic view on contact angle selection

TL;DR

This paper investigates the microscopic mechanisms determining contact angle selection on solids, generalizing classical laws and incorporating hysteresis effects through a mean field continuum approach.

Contribution

It introduces a generalized framework for understanding contact angle selection, including hysteresis, based on intermolecular forces and a mean field continuum model.

Findings

Recovered Young's law for homogeneous substrates

Demonstrated how hysteresis can be incorporated self-consistently

Compared interface shapes with disjoining pressure models

Abstract

We discuss the equilibrium condition for a liquid that partially wets a solid on the level of intermolecular forces. Using a mean field continuum description, we generalize the capillary pressure from variation of the free energy and show at what length scale the equilibrium contact angle is selected. After recovering Young's law for homogeneous substrates, it is shown how hysteresis of the contact angle can be incorporated in a self-consistent fashion. In all cases the liquid-vapor interface takes a nontrivial shape, which is compared to models using a disjoining pressure.