Quantitative study of laterally inhomogeneous wetting films

TL;DR

This study uses microscopic density functional theory to analyze the structure of wetting films and contact lines on chemically stepped substrates, comparing detailed and simplified models for accuracy.

Contribution

It introduces a refined numerical approach to model interface morphologies and line tensions, and evaluates the validity of a phenomenological model against detailed calculations.

Findings

Interface displacement model is reliable for small curvatures.

Detailed density functional calculations provide insights into line tensions.

Comparison highlights when simplified models are sufficient.

Abstract

Based on a microscopic density functional theory we calculate the internal structure of the three-phase contact line between liquid, vapor, and a confining wall as well as the morphology of liquid wetting films on a substrate exhibiting a chemical step. We present a refined numerical analysis of the nonlocal density functional which describes the interface morphologies and the corresponding line tensions. These results are compared with those predicted by a more simple phenomenological interface displacement model. Except for the case that the interface exhibits large curvatures, we find that the interface displacement model provides a quantitatively reliable description of the interfacial structures.