Preparation and photolysis of poly-p-methoxyacrylophenone and its copolymers with styrene and methyl methacrylate

Poly-p-methoxyacrylophenone (PPMeOAP) and its copolymers with styrene (PMe-OAP–S) and with methyl methacrylate (PMeOAP–MMA) were prepared. The photolysis in solution with 313 and 366 nm radiation was followed viscometrically. In solvents such as chlorobenzene and ethyl benzoate, random main-chain scission from n–π^* excited triplet state occurs. The lowest excited triplet state in formic acid and in ethylene chlorhydrin is of the character π–π^*, from which no main-chain scission occurs. In solvents in which destruction occurs, the main-chain scission is retarded by triplet quenchers, such as naphthalene, 2,5-dimethyl-2,4-hexadiene, and biphenyl. Quenching experiments indicate that the lifetime for the excited triplet state of PPMeOAP is 25 times that for polyacrylophenone. In PMeOAP–MMA copolymers, quantum yields of main-chain scissions were lower and lifetimes of excited triplets were longer than in PPMeOAP, due to hindered intramolecular photoreaction.