Studies on the role of peroxy and hydroperoxy groups in polymer photodegradation

Interactions of carbonyl singlet and triplet excited states with peroxides and hydroperoxides were examined in order to ascertain the reasons why the latter two compounds act as nearly diffusion controlled quenchers of ketone‐containing polymer photodegradation. From singlet state fluorescence quenching and laser flash photolysis measurements of triplet decays, direct interaction with the carbonyl excited states was ruled out. These processes occurred with rate constants at least one to two orders of magnitude below the diffusion controlled limit. Trapping of the 1,4‐biradical precursor to chain scission, thereby preventing its disproportionation was also tentatively eliminated. Results obtained using benzoyl peroxide suggest that quencher photodissociation into alkoxy radicals might represent the key step in the quenching of ketone‐containing polymer photodegradation.