PARAMAGNETIC CENTERS STABILIZING IN RADIOLATED POLYSTYRENE

Low-temperature radiolysis of polystyrene has been investigated by EPR method. The accumulation of stabilized electrons, radical pairs, and at doses >100 kGy – radical structures formed by two reactions – detachment and attachment of atomic hydrogen – has been traced. In the course of radiolysis at 77 K, the reaction of H addition to the double bonds of phenyl groups prevails with the formation of two isomers of cyclohexadienyl radicals (radiation yield 0.25 per 100 eV). The formation of diphenyl cyclohexadienyl radical structures with a 5-component EPR spectrum (STR constant, α = 4.5 mTl) was detected for the first time at doses above 2000 kGy. The spectra of two unknown radicals were detected and identified: breakaway radicals at the α-carbon atom of the polymer chain ~C_βH₂−C_α·(Ph)−C_βH₂− and addition radicals at the α-carbon atom ~C_αH(Ph)−C_β·(OH)−C_αH(Ph)~. Quantum chemical calculations of the radical structures of cyclohexadienyl radicals showed satisfactory agreement between the calculated and experimental data.

polystyrene, gamma irradiation, EPR spectroscopy, stabilized radicals