Photochemical behaviour of POF-Part VII. Direct and sensitized photochemistry of poly[bis-(4- isopropylphenoxy)phosphazene] in solution and films.

The direct and benzophenone-sensitized photochemistries of poly[bis(4-isopropylphenoxy)]phosphazene (PIPP) have been investigated both in solution and in film. It has been found that the presence or the absence of molecular oxygen during photolysis in solution is an important factor in inducing degradation or crosslinking, respectively, of the irradiated polymer. By contrast, during photochemistry of the polyphosphazene film, photocrosslinking is always the major process, accompanied by formation of hydroperoxides and carbonylic groups when the experiments are carried out in air. The benzophenone-sensitized hydroperoxide formation on PIPP films may be an important process for subsequent surface grafting on the polyphosphazene matrix.