Xanthate Mediated Living Free Radical Polymerization Of The Nonconjugated Vinyl Monomers

Because of the specialty of the structure of nonconjugated vinyl monomers, it's difficult to realize the living polymerization of them. Recently, the reports according to the living polymerization of nonconjugated vinyl monomers were not so much. Through the literature search, reversible addition-fragmentation chain transfer (RAFT) is the most effective method for the polymerization of nonconjugated vinyl monomers. And compared with the common dithioesters, xanthate agents were more suitable for the living polymerization of nonconjugated vinyl monomers.In this thesis, several RAFT agents with different structures were designed and synthesized. The polymerization behaviours of"less activated"vinyl monomers mediated by these RAFT agents were investigated, and several end-functionalized polymers were synthesized via RAFT polymerization technique. The main work in this thesis is summarized as following:(1) The RAFT polymerizations of three"less activated"monomers (LAMs), e.g., vinyl acetate (VAc), N-vinylcarbazole (NVC) and N-vinylpyrrolidone (NVP), were investigated mediated by a commercially available disulfide compound, isopropylxanthic disulfide (DIP), using 2, 2'-azoisobutyronitrile (AIBN) as the initiator. The polymerization behaviours of LAMs mediated by DIP demonstrated the nature of the"living"/controlled free radical polymerization. The architectures of the obtained polymers obtained were characterized by GPC, 1H NMR, UV-Vis and MALDI-TOF-MS spectra. The successful achievements will be helpful for industrial application of RAFT technique in the future.(2) Three cholesterol-functionalized xanthates with different structures were designed and synthesized. The polymerization behaviours of vinyl acetate (VAc) and Vinyl Chloroacetate (VACl), mediated by above three cholesterol-functionalized xanthates were investigated using 2,2'-azoisobutyronitrile (AIBN) as the initiator. The effect of reaction temperature, solvents and molar ratios of components on the polymerization of VAc and VACl were also investigated in detail. The polymerization behaviours of VAc and VACl mediated by these functional xanthates indicateded the chacteristics of the"living"/controlled free radical polymerization. The architectures of the polymers obtained were characterized by GPC and 1H NMR.