Dynamical density functional theory for the dewetting of evaporating thin films of nanoparticle suspensions exhibiting pattern formation

TL;DR

This paper develops a dynamical density functional theory to model pattern formation during the dewetting of evaporating nanoparticle suspensions, capturing complex structures and the effects of evaporation, transport, and contact line dynamics.

Contribution

It introduces a versatile theoretical framework that models the interplay of phase change, nanoparticle transport, and pattern formation in dewetting thin films.

Findings

The theory reproduces labyrinthine, network, and finger structures.

It reveals the role of decomposition and contact line motion in front instability.

The model can investigate various transport and evaporation effects.

Abstract

Recent experiments have shown that the striking structure formation in dewetting films of evaporating colloidal nanoparticle suspensions occurs in an ultrathin `postcursor' layer that is left behind by a mesoscopic dewetting front. Various phase change and transport processes occur in the postcursor layer, that may lead to nanoparticle deposits in the form of labyrinthine, network or strongly branched `finger' structures. We develop a versatile dynamical density functional theory to model this system which captures all these structures and may be employed to investigate the influence of evaporation/condensation, nanoparticle transport and solute transport in a differentiated way. We highlight, in particular, the influence of the subtle interplay of decomposition in the layer and contact line motion on the observed particle-induced transverse instability of the dewetting front.