Viscoelastic and poroelastic relaxations of soft solid surfaces

TL;DR

This study investigates how soft solid surfaces relax after deformation, revealing a transition from viscoelastic to poroelastic behavior through interferometric imaging, which enhances understanding of their surface mechanics.

Contribution

It provides experimental evidence of a crossover from viscoelastic to poroelastic relaxation mechanisms on soft solid surfaces using advanced imaging techniques.

Findings

Identified a crossover from viscoelastic to poroelastic relaxation.

Quantified surface deformation profiles at various scales.

Demonstrated the importance of both mechanisms in surface relaxation.

Abstract

Understanding surface mechanics of soft solids, such as soft polymeric gels, is crucial in many engineering processes, such as dynamic wetting and adhesive failure. In these situations, a combination of capillary and elastic forces drives the motion, which is balanced by dissipative mechanisms to determine the rate. While shear rheology (i.e. viscoelasticity) has long been assumed to dominate the dissipation, recent works have suggested that compressibility effects (i.e. poroelasticity) could play roles in swollen networks. We use fast interferometric imaging to quantify the relaxation of surface deformations due to a displaced contact line. By systematically measuring the profiles at different time and length scales, we experimentally observe a crossover from viscoelastic to poroelastic surface relaxations.