Free radicals and photo-oxidation of an alternating copolymer of ethylene and carbon monoxide

Reactions of formations of free radicals on photolysis of low-molecular alt ernating ethylene-carbon monoxide copolymer and its photo-oxidation are inv estigated. It is found that the photolysis occurs by the Norrish I type mec hanism with terminations of the polymer chain and formation of acyl and alk yl terminal radicals (quantum yield phi(R) similar or equal to 2 x 10(-4) a t 77 K and similar to 10(-3) at 300 K). The copolymer photo-oxidation is ch aracterized by high efficiency. In the case of doses of up to similar to 5 x 10(17) quanta/cm(2), there is a correspondence between the amount of abso rbed O-2 and the formation of gaseous products of oxidation, H2O and CO2 (p hi(oz) similar or equal to phi(gas) similar or equal to 7). At doses > 10(1 8) quanta/cm2 the yield of gaseous products is retarded, and the yield of O -2 absorption decreases by an order of 10. The gaseous products of the phot olysis and photo-oxidation involve (among H2O and CO2) also carbon monoxide , methane, ethane, propane, ethylene, acetone and hydrogen peroxide (phi = 10(-2)-10(-4)). (C) 2000 Elsevier Science Ltd. All rights reserved.