Gels: Energetics, Singularities, and Cavitation

This article studies equilibrium singular configurations of gels and addresses open questions concerning gel energetics. We model a as an incompressible, immiscible saturated mixture solid polymer solvent that sustain chemical interactions at the molecular level. assume energy consists elastic its network plus Flory-Huggins mixing. The latter involves entropic energies individual components interaction between solvent, with temperature dependent Flory parameter, $\chi $ , encoding properties solvent. In particular, good promoting mixing regime, is found below threshold value =0.5$ whereas phase separating regime develops above critical value. show cavities singularities develop in regime. find two main classes singularities: (i) drying out water possibly exiting domain through boundary, leaving behind core exposed centre gel; (ii) cavitation, response to traction on boundary or some form negative pressure, cavity can be either void flooded by straightforward unified mathematical approach treat all such based construction appropriate test functions, inspired particular states uniform swelling compression. last topic statistical mechanics rooted controversy research community, providing experimental analytic study support phantom versus affine one.