Tricriticality in thermoreversible gels

Abstract

A simple model is introduced to describe the observed coexistence of gelation and phase demixing in atactic polystyrene solutions. It is shown that the multiple equilibria conditions for molecular clustering caused by physical cross linking can lead to a characteristic feature of the phase diagram. The condition is examined for the appearance of new critical phenomena, such as a tricritical point or a triple point (or a three-phase equilibrium) as a result of interference between gelation and phase separation.