Kinetics of Ring-Opening Radical Polymerization of Vinyloxiranes

Ring-opening radical polymerization has been followed by the flash photolysis method. As an initiator radical, the arylthiyl radical (ArS˙) was used; the addition reaction rate constants of ArS˙ to vinyl monomer containing epoxy-ring such as vinyloxiranes have been determined at first. The rate constant of ring opening reaction of the adduct radical changing to ArSCH2CH CROCH2˙ were determined in the form of the relative values, which were converted to the absolute values. The ring-opening reaction rate constants were ca. 106 s−1, which indicates that the ring-opening rates are faster than usual radical propagation rates. The rate constants for vinyl monomer with 5-member ring (1,4-epoxy-1,4-dihydronaphthalene) were similarly evaluated.