Capillarity of soft amorphous solids: a microscopic model for surface stress.
The elastic deformation of a soft solid induced by capillary forces crucially relies on the excess stress inside the solid-liquid interface. While for a liquid-liquid interface this "surface stress" is strictly identical to the "surface free energy," the thermodynamic Shuttleworth equation implies that this is no longer the case when one of the phases is elastic. Here we develop a microscopic model that incorporates enthalpic interactions and entropic elasticity, based on which we explicitly compute as the surface stress and surface free energy. It is found that the compressibility of the interfacial region, through the Poisson ratio near the interface, determines the difference between surface stress and surface energy. We highlight the consequence of this finding by comparing with recent experiments and simulations on partially wetted soft substrates.
Physics of Fluids Group and MESA+ Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands.
Joost H
JH
Weijs
Physics of Fluids Group and MESA+ Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands.
Jacco H
JH
Snoeijer
Physique et Mécanique des Milieux Hétérogènes, UMR 7636 ESPCI -CNRS, Univ. Paris-Diderot, 10 rue Vauquelin, 75005, Paris.
Bruno
B
Andreotti