Kinetics of radical polymerization of methyl methacrylate initiated with dimethyl 2,2′-azodiisobutyrate

The kinetics of free-radical bulk polymerization of methyl methacrylate with dimethyl 2,2′-azodiisobutyrate as an initiator was investigated at 40, 60, and 80°C. Non-ideal polymerization behaviour was observed when the initiator concentration was varied by a factor of more than one thousand. This departure from classical polymerization kinetics is discussed in terms of primary radical termination and a chain length dependent termination rate constant, with the structural similarity of both primary and polymeric radicals facilitating the treatment very much. The kinetic analysis indicates that in the polymerization of methyl methacrylate the termination rate constant is a function of the degree of polymerization of the involved macroradicals.