Aqueous polymerization of methyl methacrylate initiated by the redox system Ce(IV)-D-Glucose. II: Effect of reaction conditions on polymer molecular weight

The dependence of molecular weight of poly(methyl methacrylate) on reaction conditions, as polymerized in aqueous nitric acid with the redox system ceric ammonium nitrate-glucose, has been studied. The average molecular weights and molecular weight distributions were determined by size-exclusion chromatography. The degree of polymerization was found to increase in the course of a run and was also affected by changes of Ce(IV) and glucose concentrations in the range where the rate of polymerization increased, but not where the rate was independent of Ce(IV) concentration and decreased with glucose concentration. The average molecular weights can be controlled by variations in monomer concentration and in temperature. The polymerization rate was found to attain a maximum with nitric acid concentration whereas the rate of ceric ion consumption increased. A fall in the degree of polymerization was observed on increasing the acid concentration. The effect of nitrate ion concentration as well as of that of certain water-miscible solvents on the above-mentioned parameters has also been studied.