Comportement des hydroperoxydes pendant la photo-oxydation d'un copolymère de styrène-butadiène

During the photo-oxidation at 254 nm of a styrene-butadiene copolymer, the quenching by hydroperoxides of singlet excited states of phenyl groups (and to a small extent of excimers) yield their photosensitized decomposition. The created radicals initiate hydroperoxide propagation reaction into the polymeric bulk. The natures of the various phases, through which this chain reaction develops, depend on the amount of available polymeric sites which can be easily oxidized (particularly allylic positions). Moreover, according to their behaviour, hydroperoxides have been placed in two classes: the “active” groups which are located at a stationary concentration in the vicinity of phenyl groups and the “inactive” groups which are outside this active sphere and remain stable after formation because they are not involved in the primary photophysical process.