Enhanced degradation of cellulose acetate films in the copresence of triphenylsulfonium salt and benzophenone

To investigate whether benzophenone (BP) enhances triphenylsulfonium salt (TPS) degradation of cellulose acetate (CA) during photoirradiation, CA (degree of substitution = 2.45) films containing TPS and BP were prepared, and their degradative behavior was examined under simulated solar exposure. The irradiation-evoked generation of acetic acid from the films was greater in the copresence of TPS and BP than in the sole presence of TPS. This result indicates that the TPS was activated by BP to produce Bronsted acid, which induced the deacetylation of CA effectively. As a possible mechanism for this activation of TPS, we postulated that the TPS oxidized free-radical species induced by the photoreaction of BP, which was followed by the generation of Bronsted acid. The activation of TPS by BP did not appear to significantly accelerate the main-chain cleavage of CA because size exclusion chromatography data did not reveal any decrease in the molecular weight of CA. (C) 2008 Wiley Periodicals, Inc.