Photoactive azobenzene polymers containing carbazole chromophores

Polymeric systems containing side-chain photoactive chromophores were prepared by free-radical copolymerization of N-vinylcarbazole with 4-methacryloyloxyazobenzene and 4-methacryloyloxy-4'-cyanoazobenzene. The resulting materials were characterized by size exclusion chromatography, TGA and DSC thermal analysis, FT-IR, H-1 NMR, UV-vis, and fluorescence spectroscopy and photoisomerization experiments. In all cases, the copolymer composition was almost independent of the feed composition, in agreement with the strong tendency of the investigated monomers to alternating copolymerization. Spectroscopic and thermal data clearly highlighted the occurrence of charge-transfer electronic interactions between electron-rich carbazole rings and electron-poor azobenzene chromophores. These interactions facilitate the trans-cis photoisomerization of azobenzene side-chains.