Elasto-capillary meniscus: Pulling out a soft strip sticking to a liquid surface

TL;DR

This paper investigates the shape and extraction force of a soft elastic strip on a liquid surface, revealing how elasticity influences the maximum sustainable liquid height and the force needed for detachment.

Contribution

It introduces a combined experimental and theoretical analysis of elasto-capillary menisci, extending classical rigid-object models to include elastic properties of the strip.

Findings

Existence of a maximum liquid height before detachment

Elasticity increases the critical extraction force

Theoretical predictions match experimental results

Abstract

A liquid surface touching a solid usually deforms in a near-wall meniscus region. In this work, we replace part of the free surface with a soft polymer and examine the shape of this elasto-capillary meniscus, result of the interplay between elasticity, capillarity and hydrostatic pressure. We focus particularly on the extraction threshold for the soft object. Indeed, we demonstrate both experimentally and theoretically the existence of a limit height of liquid tenable before breakdown of the compound, and extraction of the object. Such an extraction force is known since Laplace and Gay-Lussac, but only in the context of rigid floating objects. We revisit this classical problem by adding the elastic ingredient and predict the extraction force in terms of the strip elastic properties. It is finally shown that the critical force can be increased with elasticity, as is commonplace in adhesion phenomena