| Abstract: | Polymerizations of some vinyl monomers were carried out with 2,2′-azobisisobutyronitrile at 60°C in the presence of a methyl methacrylate (MMA) dimer ( I ) or a MMA polymer ( II ) with a double bond at their ends to confirm the polymerization reactivity of unsaturated end group generated during the disproportionation in termination reaction of MMA polymerization. It was found that the polymerizations of α-monosubstituted monomers have been much retarded than those of α,α-disubstituted monomers by the addition of I . Kinetic study on MMA and methyl acrylate polymerizations showed that the rate constant for the reaction of a propagating radical with I was 5.4 and 29.2 L/mol s in their polymerizations, respectively. ESR study using I and II suggested that an addition reaction was a predominant mechanism for the reaction of an unsaturated end group with a radical rather than a hydrogen abstraction. |
