Hydroperoxides as intermediates responsible for wavelength effects in photooxidation reactions

A quantitative study of a model elastomer was performed to gain a deeper insight into photooxidation processes. Since the twofold role of hydroperoxides as excited sensitizer quenchers, and radical initiators has been amply demonstrated, we described the mechanism of energy transfer to repulsive excited states of these substances and quantitatively determined their distribution in the polymeric material, according to their reactivity. In addition, two irradiation wavelengths (λ = 254 nm and λ = 313 nm) were used to demonstrate that behavior of hydroperoxides depends on the nature and the concentration of excited chromophoric groups and accounts for the macroscopic wavelength effect usually observed in the photooxidation of polymers.