Unstable intermediates. Part 108.—Electron spin resonance study of radicals formed by the irradiation of polycarbonate and model compounds

Abstract

E.s.r. spectra from poly[(oxycarbonyloxy-p-phenylene)isopropylidene-(p-phenylene)]γ- or u.-v.-irradiated at 77 K showed features characteristic of radical pairs in addition to central features assigned mainly to phenoxy radicals. Their decay on slow annealing has been studied and compared with those of similar radicals and radical pairs in γ-irradiated diphenyl carbonate. In the latter the pairs decay rapidly at temperatures far lower than that required for loss of the non-paired radicals. In contrast, paired and non-paired species showed similar decay characteristics in the polymer. Other aspects of radical pair-trapping and decay are reported and discussed.