Synthesis Of Dithiocarbamates Bearing Azobenzene Group And Use For RAFT Polymerization

Three novel dithiocarbamates bearing azobenzene group, 2-(phenylazo- phenoxy- carbonyl)prop-2-yl 9H-carbazole-9-carbodithioate (APCDT), 2-(4-nitro-Phenylazo- Phenoxy-Carbonyl)Prop-2-yl 9H-Carbazole-9-Carbodithioate (ANPCDT), 2-(4-cyano- Phenylazo-Phenoxy-Carbonyl)Prop-2-yl 9H-Carbazole-9-Carbodithioate (ACPCDT) were synthesized and successfully used in the RAFT polymerization of vinyl monomers. The results were shown as below.(1). The novel dithiocarbamate bearing azobenzene group, APCDT was synthesized and successfully used as a RAFT agent in the polymerization of methyl methacrylate(MMA). The results showed that the controllability to the polymerization of MMA was promoted with APCDT as RAFT agent compared to 2-(ethoxycarbonyl)prop-2-yl 9H-carbazole- 9-carbodithioate (EPCDT) under the same experimental conditions. The reason was attributed to the higher chain transfer constant of APCDT than that of EPCDT in the presence of more bulkier and more electrophilic azobenzene moiety. In addition, the RAFT polymerizations of St and methylacrylate (MA) using APCDT as the RAFT agent were also carried out. The results showed that APCDT was an effective RAFT agent for thermal initiation polymerization of St and AIBN-initiated polymerization of MA. In addition, the UV and fluorescence properties of azobenzene-terminated polymers were massured.(2). Based on the system 1, different RAFT agents with different substitute on azobenzene group in the R group were synthesized and used for RAFT polymerization of MMA. At the same time, three azobenzene-based dithiocarbamates were used as RAFT agents for thermal polymerization of St. The results showed that the different substitute on azobenzene in dithiocarbamates would not influence the controllability on RAFT polymerization of MMA and showed the similar character with APCDT for RAFT polymerization of MMA. In addition, three different azobenzene-based dithiocarbamates are effective RAFT agents for RAFT polymerization of St. The polymerization of St with thermal initiation is influenced by the chemical structure of the group R in dithiocarbamates. Both ACPCDT and ANPCDT mediate a much slower polymerization compared to that mediated by APCDT. Furthermore, Optical properties of dithiocarbamates and corresponding polymers terminated with carbazole and azobenzene groups have been investigated.