Cationic photopolymerization of epoxides by direct and sensitized photolysis of onium tetrakis(pentafluorophenyl)borate initiators

摘要

Cationic photopolymerization of epoxides by the direct and sensitized photolysis of eight onium tetrakis(pentafluorophenyl)borates as initiators has been investigated. The relative reactivity of the onium borates on the photopolymerization was studied by the measurement of spectral sensitivity and by real time Fourier transform infrared spectroscopy. The kinetics of the photopolymerization by the sensitized photolysis was different from that of the direct photolysis. Several onium borates were sensitized by the excited singlet state of the anthracenes (nonsubstituted anthracene and 9-methyl- and 9,10-dimethylanthracene), and the rates of polymerization increased with decreasing free energy changes between the onium borates and the excited singlet state of 9-methylanthracene. The acid generated by the photodecomposition of the onium borates produced nonacidic products by heating.