Effects of diphenyliodonium hexafluorophosphate in the radiation‐induced cationic polymerization of styrene. Formation and decay processes of styrene dimer radical cation

Abstract

AbstractThe radiation‐induced cationic polymerization of styrene in methylene chloride is promoted by the addition of (C6H5)2IPF6, while the polymerization is inhibited in the presence of (C6H5)2ICl. The pulse radiolysis study reveals that both the yield and the lifetime of styrene dimer radical cation are increased by the addition of (C6H5)2IPF6, and, on the contrary, both are decreased in the presence of (C6H5)2ICl. The kinetic plots for the decay of the dimer radical cation in the presence and absence of the salts show that the decay is predominantly due to the neutralization with Cl−. The lengthening of the lifetime of the dimer radical cation in the presence of (C6H5)2IPF6 is believed to be due to the stabilization toward Cl− by the ion‐pair formation with PF6−. Slow formation of the dimer radical cation was also observed in the presence of (C6H5)2IPF6, which is attributable to the oxidation of radical species by the salt followed by the charge transfer to monomer. Such a slow formation of radical cation in the presence of (C6H5)2IPF6 was confirmed with biphenyl in methylene chloride.