Vinyl polymerization by cobaltic ions in aqueous solution: Part I. Polymerization of methyl methacrylate

Polymerization of methyl methacrylate initiated by cobaltic ions in perchloric, nitric and sulfuric acids was studied in the temperature range 15–25°C. In all three acids, water oxidation occurred as a side reaction. In HClO4 and HNO3 media monomer oxidation was shown to be an additional complicating feature. Rates of cobaltic ion disappearance, monomer disappearance, and chain lengths of polymers were measured with variations in [M], [Co3+], [H+], initially added [Co2+], and temperature. In HClO4 and HNO3 experimental results favored simultaneous initiation by Co3+ and CoOH2+ species, while in H2SO4, Co3+ ions alone were the active entities. An appropriate kinetic scheme to fit all the experimental observations is proposed. The various rate constants were evaluated.