Soft wetting and the Shuttleworth effect, at the crossroads between thermodynamics and mechanics

TL;DR

This paper explores the complex interplay between thermodynamics and mechanics in soft wetting, emphasizing the Shuttleworth effect's role in deformable elastic materials and its implications for capillary forces and surface stresses.

Contribution

It highlights the significance of the Shuttleworth effect in soft wetting, bridging microscopic and macroscopic perspectives, and discusses its impact on elastic singularities and capillary forces.

Findings

Identification of elastic singularities in soft wetting

Demonstration of the difference between surface stress and free energy

Discussion of open issues in the physics of soft wetting

Abstract

Extremely compliant elastic materials, such as thin membranes or soft gels, can be deformed when wetted by a liquid drop. It is commonly assumed that the solid capillarity in "soft wetting" can be treated in the same manner as liquid surface tension. However, the physical chemistry of a solid interface is itself affected by any distortion with respect to the elastic reference state. This gives rise to phenomena that have no counterpart in liquids: the mechanical surface stress is different from the excess free energy in surface. Here we point out some striking consequences of this "Shuttleworth effect" in the context of wetting on deformable substrates, such as the appearance of elastic singularities and unconventional capillary forces. We provide a synthesis between different viewpoints on soft wetting (microscopic and macroscopic, mechanics and thermodynamics), and point out key open issues in the field.