Cationic Polymerization of <i>p</i>-Methoxystyrene in Water with Dodecylbenzenesulfonic Acid and Ytterbium Triflate:  Evidence for an Inverse Emulsion Process

Abstract

The cationic polymerization of p-methoxystyrene in water using dodecylbenzenesulfonic acid as a surfactant and ytterbium triflate as a catalyst was studied in terms of kinetics and physicochemistry. Preliminary stability studies showed that stable inverse (water in monomer) emulsions were obtained using excess catalyst and cocatalyst. Rates of polymerization and molar masses were respectively found slower and larger than for direct emulsion processes, in accordance with previous results published by Sawamoto on similar systems. The presence of the catalyst did not affect the mechanism scheme of ionic polymerization in aqueous dispersion; i.e., the polymerization is interfacial, and physicochemical issues govern molar masses.