Thermal-induced conversion of maleic and fumaric acid anion radicals in poly(methyl methacrylate)

Thermal-induced conversion of maleic and fumaric acid anion radicals produced by ..gamma.. irradiation at 77/sup 0/K in poly(methyl methacrylate) (PMMA) was studied by electron spin resonance (ESR) and optical absorption spectroscopic measurements. The ESR spectra of these acid anion radicals change into two-line spectra with a line separation of ca. 10 G by thermal annealing. This spectrum is assigned to a protonated radical of each acid anion radical. Anion radicals of the solutes are relatively stable below the ..gamma.. transition point of PMMA and the conversion reaction takes place near this point. This means that the molecular motion of matrix molecule affects the radical conversion reaction.