Gradient dynamics description for films of mixtures and suspensions - the case of dewetting triggered by coupled film height and concentration fluctuations

TL;DR

This paper introduces a gradient dynamics model for thin liquid films of mixtures and suspensions, capturing coupled dewetting and decomposition driven by height and concentration fluctuations, with nonlinear simulations showing steady-state profiles.

Contribution

It develops a novel gradient dynamics framework based on an extended interface Hamiltonian for modeling complex structuring in thin films of mixtures and suspensions.

Findings

Coupled dewetting can be triggered by concentration and height fluctuations.

Long-range van der Waals forces influence film stability.

Nonlinear simulations reveal steady film profiles.

Abstract

A gradient dynamics model based on an extended interface Hamiltonian is presented that is able to describe the dynamics of structuring processes in thin films of liquid mixtures, solutions and suspensions on solid substrates including coupled dewetting and decomposition. After discussing known limiting cases the model is employed to investigate the dewetting of thin films of liquid mixtures and suspensions under the influence of effective long-range van der Waals forces that depend on solute concentration. The occurring fluxes are discussed and it is shown that spinodal dewetting may be triggered through the coupling of film height and concentration fluctuations. Fully nonlinear calculations provide the time evolution and resulting steady film height and concentration profiles.