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 (CH2 = CHCROCH2) have been determined at first. The rate constant of ring opening reaction of the adduct radical (ArSCH2C.HCROCH2) 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. 10(6) 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.