Preparation and photochemical properties of polymethacrylic esters of para-acylated 2-phenoxyethanols

For studying the photochemistry of carbonyl chromophores in the side-chain, methacrylic esters of para-acylated 2-phenoxyethanols (CH₂ = C(CH₃) · CO · O · CH₂ · CH₂O · C₆H₄ · CO · R), soluble copolymers with styrene and soluble homopolymers were prepared. Comparison of low temperature emission spectra of model compounds, homopolymers and copolymers doped in polystyrene film indicated some interaction between the excited and the ground state structural units in homopolymers. Quantum yield of main chain scission of copolymers of styrene with monomers 1–3 (R = CH₃, C₂H₅, C₆H₅) at 313 nm radiation in benzene were about 10^?4; the cross-linking was the main reaction for copolymer styrene/monomer 4 (R = C₆H₅CH₂). On exposure of copolymers styrene/monomers 1–4 and polystyrene doped with model compounds in film to 313 nm radiation in air, accelerated photo-oxidation occurs as well as cross-linking. Only chromophores of monomers 3 and 4 were effective as sensitizers of photochemical addition of maleic anhydride to benzene by radiation with γ > 340 nm. The difference in the efficiency between model compounds and copolymers on the one hand and a homopolymer on the other hand is due to self-quenching.