Spreading and absorption of silicone oil droplets on silicone elastomer films

TL;DR

This study explores how silicone oil droplets spread and absorb on soft silicone elastomer films, revealing deviations from classical laws due to the films' mechanical properties and absorption effects.

Contribution

It introduces a phenomenological model that incorporates absorption and mechanical effects to explain spreading dynamics on soft elastomer films.

Findings

Deviations from Tanner's law observed on soft elastomer films.

Spreading behavior depends on film thickness and stiffness.

Absorption influences the spreading rate and pattern.

Abstract

When a liquid droplet completely wets a hard substrate, its spreading dynamics follow Tanner's law, with the droplet radius growing as the one-tenth power of time. Here, we investigate how these dynamics change when silicone oil droplets spread on soft silicone elastomer and gel films supported by a rigid silicon substrate. While the droplets fully wet the elastomer surface, they also simultaneously swell the elastomer film. By varying the film thickness, we observe deviations from the classical power-law scaling, which we interpret in terms of changes to the effective stiffness and the absorption potential of the system. We describe the spreading behavior using a phenomenological model that accounts for both absorption and mechanical contributions.