PHOTOSENSITIZED INITIATION OF POLYMERIZATION OF METHYL-METHACRYLATE BY TRIOSMIUM DODECACARBONYL

The kinetic study of the mechanism of photosensitized initiation of methyl methacrylate (MMA) polymerization by Os3(CO)12/CCl4 at lambda = 365 nm is presented. The monomer is found to participate in the initiation process. Observed initiation by Os3(CO)12/MMA is explained in the light of a hydrogen abstraction process and Os3(CO)12/CCl4/MMA as an electron transfer process. The ratio of the rate constants of the component reactions were evaluated. The observed values of the kinetic parameter k(p)k(t)-1/2 demonstrate that retardation does not occur in these reactions. The quantum yield of photoinitiation of Os3(CO)12/CCl4/MMA is significantly low, i.e., approximately 0.013 as compared to that of other metal carbonyls such as Mn2(CO)10/CCl4/MMA and Re2(CO)10/CCl4/MMA, where the quantum yield of initiation is reported to be close to unity.