Photodegradation of cis‐1,4‐polyisoprene in solution sensitized by the addition of nitroso compounds in the presence of visible light

It was found that apart from chloronitroso compounds bromonitroso and nitronitroso compounds also sensitize the photodegradation by visible light of cis‐1,4‐polyisoprene in solution. The investigation of the kinetics of the relative viscosity decrease in solutions containing chloronitroso compounds and stable free radicals, e.g., α, α‐diphenyl‐β‐picryl hydrazyl (DPPH), di(4‐methoxyphenylo)‐N‐oxide, 2,2,4‐trimethyl‐6‐ethoxy‐1,2‐dihydroquinolin‐N‐oxide, shows that the addition of stable radicals does not prevent the photochemical reaction, but merely slows down its rate. The present investigation of the photodegradation mechanism of cis‐1,4‐polyisoprene in solution, induced by the addition of chloronitroso compounds, excludes the possibility of a direct transfer of light energy over the donor‐acceptor complex, and shows that the degradation reaction is due to free radicals formed by the decomposition of the sensitizing agent.