The photochemistry of bisphenol-A polycarbonate reconsidered

Abstract Dual photochemistry is occurring in a bisphenol-A based polycarbonate. At short wavelengths, the photo-Fries rearrangements are not the only processes observed. The radicals primarily formed in direct photoscission lead to hydrodiphenyl units, and secondary photoreactions of the photo-Fries products are influenced by oxygen. At long wavelengths, a photo-induced oxidation is occurring and a fairly high concentration of tertiary hydroperoxides, stable at 80°C, is observed. In polychromatic light peaking at 310 nm, both mechanisms are involved, the photo-Fries photoproducts protecting only temporarily the polycarbonate against the photo-induced oxidation; hydroperoxides reached a lower stationary concentration than with 365 nm excitation.