Radical polymerization of styrene initiated by benzopinacolates: kinetics and comments concerning the reaction mechanism

The present paper reports an investigation on the “pseudo-living” radical chain propagation process in the case of the styrene polymerization initiated by benzopinacolates. Two steps were observed, as in earlier reported investigations. Oligomers were formed first at low monomer conversions, due to the rapid chain-termination by the primary radicals present at a high concentration. Polymerization takes place only after consumption of the major part of these radicals. Experiments carried out on model molecules representative of the oligomer chain-ends yielded evidence that these species are unactive, they do not undergo further thermal cleavage. The in the literature reported insertion process was not confirmed for the styrene polymerization.