Reactions of radiation-induced degradation of poly(methyl methacrylate) and polysilanes

In order to elucidate chemical reactions of radiation-induced degradation of poly(methyl methacrylate) and poly(cyclohexylmethylsilane) as typical examples of radiation-degrading polymers, the yield of main-chain scission, G(S), was studied as a function of irradiation temperature in the range 77-300 K. It was found to be independent of the temperature at 77-300 K for purified poly(methyl methacrylate) and to decrease with lowering temperature below 175 K to zero-value at 77 K for poly(cyclohexylmethylsilane). Based on these results together with the behavior of free radicals observed by the ESR method, the reactions responsible for the radiation-degradation are discussed for these polymers