Polymerization of methyl methacrylate in the presence of molecular oxygen — a kinetic study

Methyl methacrylate was polymerized in aqueous medium initiated by a copper(II)-ascorbic acidoxygen system at 40°C and a kinetic study of the reaction is presented. The rate of polymerization, R_p showed an increase, constancy and then a decrease with increase in the Cu²⁺]. The order with respect to Cu²⁺] was 0.5 in the rate increase region. The order in monomer concentration changed gradually from 1.0 to 2.0 with increase in Cu²⁺]. R_p became independent of ascorbic acid (AA) concentration and oxygen concentration at high concentrations. These results indicate that termination by mutual interaction of chain radicals predominates at low Cu²⁺] while termination was exclusively by metal ions at high Cu²⁺]. R_p was also observed to increase with temperature and ionic strength and to K_p/K_t^1/2 value was calculated and compared with literature values. Chain lengths were determined by viscometry for the polymers obtained under various experimental conditions.