Rate Constants in the Free-Radical Polymerization of Perdeuterated Styrene

Kinetic studies of the AIBN- and BPO-initiated free-radical polymerization of perdeuterated styrene (S-D8, styrene[α,β,2,3,4,5,6-2H8]) at 30-90°C were carried out. the average lifetimes of growing PS-D8 radicals in the photosensitized polymerization of the monomer were determined at 15, 20, and 25°C by the rotating-sector technique. the propagation rate constant kp was found to be 3.63 × 107 e-31500/8314T and the termination rate constant kt, to be 2.55 × 1010 e-14200/8314T. the activation energy for the propagation reaction of S-D8 is fairly close to that of styrene (S-H8), but the activation energy for the termination step of S-D8 is 1.5 times higher than that for S-H8. the deuterium isotopic effect on the rates of the polymerization was found to be inverse at all temperatures studied.