The role of crosslinking density in surface stress and surface energy of soft solids

Abstract

Surface stress and surface energy are two fundamental parameters that determine the surface properties of any materials. While it is commonly believed that the surface stress and surface energy of liquids are identical, the relationship between the two parameters in soft polymeric gels remains debatable. In this work, we measured the surface stress and surface energy of soft silicone gels with varying weight ratios of crosslinkers in soft wetting experiments. Above a critical density, $k_0$, the surface stress was found to increase significantly with crosslinking density while the surface energy remained unchanged. In this regime, we can estimate a non-zero surface elastic modulus that also increases with the ratio of crosslinkers. By comparing the surface mechanics of the soft gels with their bulk rheology, the surface properties near the critical density $k_0$ were found to be closely related to the underlying percolation transition of the polymer networks.

9 pages, 7 figures

References in corpus (4)

• The fracture of highly deformable soft materials: A tale of two length scales
• Modelling Elastically-Mediated Liquid-Liquid Phase Separation
• Viscoelastic and poroelastic relaxations of soft solid surfaces
• Droplets sit and slide anisotropically on soft, stretched substrates

Cited by in corpus (6)

• Wetting on Silicone Surfaces
• Elasticity-Controlled Jamming Criticality in Soft Composite Solids
• Stick-Slip Contact Line Motion on Kelvin-Voigt Model Substrates
• Emergence and Growth Dynamics of Wetting-induced Phase Separation on Soft Solids
• Non-monotonic Rheology and Stress Heterogeneity in confined Granular suspensions
• Mechanical non-reciprocity programmed by shear jamming in soft composite solids