FORMATION AND LOSS OF METHYL RADICALS IN IRRADIATED SILOXANE BLOCK-COPOLYMERS

The formation of methyl radicals in irradiated dimethylphenyl silsesqu ioxane block copolymers has been studied. The introduction of phenyl s ilsesquioxane blocks into a macromolecule of block copolymer increases stability of the -->Si-CH3 bond as compared to the case of poly(dimet hylsiloxane). The yield of methyl radicals is affected by processes of the interphase energy transfer. The loss kinetics of methyl radicals in block copolymers has been studied at 77 K. The methyl radicals in b lock copolymers are predominantly lost by the reaction of H atom abstr action from the dimethylsiloxane block. The radical loss kinetics exhi bits a ''retarded'' character.