Photo and thermal polymerization sensitized by donor–acceptor interaction. I. N-vinyl-carbazole–acrylonitrile and related systems

Spontaneous photo and thermal polymerization of N-vinylcarbazole (VCZ)–acrylonitrile (AN), VCZ–acetonitrile, AN-N-ethylcarbazole, and AN-ferrocene were studied. These combinations of electron donor with acceptor were thermally rather stable but showed prominent photopolymerizability when the systems were irradiated by near ultraviolet light. The VCZ–AN system showed multireactivity producing VCZ polymer and a copolymer of VCZ with AN. The composition of copolymer was approximately the same as that of polymer produced in radical copolymerization. The effects of additives (DPPH, NH₃, H₂O, air) indicated simultaneous occurrence of cationic and radical polymerization in the AN–VCZ and acetonitrile–VCZ systems. The results were interpreted on the assumption of initial formation of a cation radical–anion radical pair. The ratio of cationic to radical polymerization differed for photo and thermal polymerization. In no case was anionic polymerization detected.