PHOTOCHEMICAL BEHAVIOR OF CINNAMOYL-CONTAINING CRYSTALLINE POLYMERS WITH COMB-LIKE STRUCTURE

Amorphous and crystalline comb-like poly(methacrylamides) containing cinnamoyl moieties in the side chain were synthesized and characterized. On UV-irradiation these polymers and related monomeric model compounds undergo E-Z photoisomerization, [2 + 2] photocycloaddition and photo-Fries rearrangement. The competition between these photoreactions was investigated in solution and solid films. The quantum yield of the photocycloaddition and the maximum of conversion of chromophores are much higher in solutions and in films for the crystalline homopolymer compared to the amorphous copolymer. The disappearance of crystallinity caused by isomerization in solution and in films caused by cycloaddition was demonstrated by means of DSC measurements. In films with side-chain crystallinity the quantum yield of cycloaddition increases with rising temperature but falls drastically above the melting point. The crystallinity of the polymer influences photoreactivity of the cinnamoyl moiety, and, on the other side, photoisomerization and cycloaddition destroy the crystalline order.