RADICAL POLYMERIZATION OF STYRENE INITIATED BY BENZOPINACOLATES - KINETICS AND COMMENTS CONCERNING THE REACTION-MECHANISM

The present paper reports an investigation on the ''pseudo-living'' ra dical chain propagation process in the case of the styrene polymerizat ion initiated by benzopinacolates. Two steps were observed, as in earl ier reported investigations. Oligomers were formed first at low monome r conversions, due to the rapid chain-termination by the primary radic als present at a high concentration. Polymerization takes place only a fter consumption of the major part of these radicals. Experiments carr ied out on model molecules representative of the oligomer chain-ends y ielded evidence that these species are unactive, they do not undergo f urther thermal cleavage. The in the literature reported insertion proc ess was not confirmed for the styrene polymerization.