The photochemical reaction of
N-ethylcarbazole (EtCz) and carbon tetrabromide (CTB) yields a dye of EtCz trimer (similar to triphenylmethane dye) by a multi-step reaction of EtCz with CTB. In the current study, we applied the principles of this reaction to polymer systems of poly [2-(9-carbazolyl) ethyl methacrylate] (PCzEMA) with CTB. The irradiation of PCzEMA film doped with CTB (CTB/PCzEMA) induced the dimerization between two Cz chromophores, which was monitored by the increase of absorption at 670nm. Since the reactive intermediate of Cz that was substituted with CBr
2 was stable, the rate of dimerization gradually accelerated as the sample was allowed to warm in the dark. The CTB/PCzEMA system does not form a trimer of Cz chromophores which is similar to triphenylmethane dye, but the dimerization reaction of the chromophoric groups resulted in photocrosslinking of the PCzEMA film. Then, the photosensitivity of CTB/PCzEMA film was compared with CTB/polyvinylcarbazole and polyvinyl cinnamate films through irradiation with a carbon arc lamp.
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