ARRESTED-VOLUME PHASE-TRANSITION OF A GEL AROUND A HOLE

When there is a hole in a chemically cross-linked gel, the phase transition from swollen to shrunken phase starts at the free surface of the hole. The growth of the new phase is, however, arrested eventually around the hole with a finite thickness depending on controlling parameters such as temperature. This phenomenon is in strong contrast with the condensation of vapour under constant pressure, and exemplifies the inapplicability of Gibbs's phase rule to coherent solids. We give a qualitative argument for it and then demonstrate it by a simple model calculation.