Wetting dynamics under periodic switching on different scales: Characterization and mechanisms

TL;DR

This paper investigates how droplets behave on switchable wettability surfaces across various switching frequencies, combining molecular dynamics, continuum models, and simple theories to understand the underlying mechanisms.

Contribution

It provides a comprehensive comparison of molecular and continuum models for wetting dynamics under periodic switching, enhancing understanding of the mechanisms involved.

Findings

Molecular dynamics and thin-film models agree on wetting behavior.

Simple models like MKT accurately predict wetting dynamics.

Wetting behavior depends strongly on switching frequency.

Abstract

The development of substrates with a switchable wettability is on a fast pace. The limit of switching frequencies and contact angle differences between substrate states are steadily pushed further. We investigate the behavior of a droplet on a homogeneous substrate, which is switched between two wettabilities for a large range of switching frequencies. Here, we are particularly interested in the dependence of the wetting behavior on the switching frequency. We show, that results obtained on the particle level via molecular dynamics simulations and on the continuum level via the thin-film model are consistent. Predictions of simple models as the molecular theory of wetting (MKT) and analytical calculations based on the MKT also show good agreement and offer deeper insights into the underlying mechanisms.