Copolymerization of N-vinylcarbazole and vinyl acetate via reversible addition-fragmentation chain transfer (RAFT) polymerization

The reversible addition-fragmentation chain transfer (RAFT) random copolymerization of N-vinylcarbazole (NVC) and vinyl acetate (VAc) was carried out using s-benzyl-o-ethyl dithiocarbonate (BED) as the chain transfer agent and 2,2'-azoisobutyronitrile (AIBN) as the initiator in 1,4-dioxane solution at 70 degrees C. The polymerization showed the characteristics of 'living' free radical polymerization behaviors: first order kinetics, linear relationships between molecular weight and conversion, and narrow polydispersity of the polymers. The reactivity ratios of NVC and VAc were calculated via the Kelen-Tudos (KT) and non-linear error in variable (EVM) methods and showed as r(1)=1.938 +/- 0.191, r(2) = 0.116 +/- 0.106. The thermal behavior of the copolymers with different content of NVC and VAc was investigated by DSC and TGA. The results showed that the introduction of a VAc segment into copolymer significantly reduced the T-g of the NVC homopolymers. FT-IR spectra, fluorescence spectra, and cyclic voltammetric behavior of these copolymers were also measured and compared with those of NVC homopolymers. The copolymers showed similar oxidative behavior to the NVC homopolymer. However, there was only one reductive potential peak shown for the copolymers at about 0.058 V.