Aqueous polymerization of methyl methacrylate initiated by Ce(IV)-disaccharide redox systems. effects of acid concentration and additives

Abstract

Polymerization of methyl methacrylate initiated by ceric ammonium nitrate in combination with maltose and cellobiose has been investigated in aqueous nitric acid. The effects of nitric acid and nitrate ion concentrations on the initial rate of polymerization as well as on the rate of ceric ion consumption and polymer molecular weight have been studied. The rate of polymerization initially increased rapidly with nitric acid concentration to a maximum when the nitrate ion concentration was kept constant, then decreased and levelled off at higher acid concentrations. The rate of ceric ion consumption increased on increasing the acid concentration, but became independent at high concentrations. Increase in the nitrate ion concentration at constant nitric acid concentration caused both rates to fall. The average molecular weights decreased with increasing acid concentration, but increased slightly with increasing concentration of nitrate ion. The effects of certain water-miscible organic solvents have also been examined. The rate of polymerization is depressed and a remarkable decrease in the molecular weight was observed in their presence, whereas the rate of ceric ion disappearance increased notably.