THERMOREVERSIBLE GELATION OF SOLUTIONS OF SYNDIOTACTIC POLY(METHYL METHACRYLATE) IN TOLUENE - A 2-STEP MECHANISM

The thermoreversible gelation of solutions of syndiotactic poly(methyl methacrylate) in toluene has been studied by different experimental techniques. A combination of calorimetric, infrared, fluorescence, light scattering, and theological observations supports the two-step gelation mechanism, proposed in a previous paper. A fast intramolecular conformational change is followed by an intermolecular association. The change in molecular mobility during the gelation process has been followed by H-1 NMR. Further support for the two-step mechanism has been found in the temperature dependence of the fluorescence properties of a probe covalently attached to the polymer chain. Finally, a concentration-temperature diagram for the polymer-solvent system has been constructed;