Reversible gels of synthetic polymers: Phase relations, formation mechanisms and structure

The complex problem of thermoreversible gelation of solutions of synthetic polymers is discussed. Several possible mechanisms, based on supramolecular structure formation in solution, are discussed. The gelation of polyethylene solutions illustrates the structure formation through lamellar, folded chain crystallization. Gelation of solutions of stereoisomers of polystyrene and poly(methyl methacrylate) is more complex and two mechanisms can are proposed. The complex temperature‐concentration phase diagrams of syndiotactic polystyrene/solvent systems illustrate the competition between gelation by crystallization and the formation of elastic gels. The influence of chain conformation, participation of the solvent in the structure formation and the influence of solvent quality is discussed. Insight in the formation mechanism of elastic gels is obtained through the study of the gelation of solutions of syndiotactic poly(methyl methacrylate).