| There are two kinds of free radical polymerization, one is conventional free radical polymerization, and another is living free radical polymerization. The molecular weight controlled and narrow molecular weight distribution polymer is easy obtained by living free radical polymerization. Polymer chemists pay more and more attention to it.First 1, 4-dibromomethylbenen was successfully synthesized by the reaction of NBS and xylene using BPO as catalyst. It was used as the difunctional initiator in the atom transfer radical polymerization. The polymerization of ethyl methacrylate (EMA) was well controlled with the linear increase of molecular weights (Mn) with conversion and relatively low polydispersities throughout the polymerization. The block copolymerizaition of styrene (St) and EMA or butyl methacrylate (BMA), methyl methacrylate (MMA) were synthesized. In the first step one of the monomers was polymerized in the bulk using the initiating system 1, 4-dibromomethylbenen/CuBr/2, 2'-bipyrindine in a mole ratio of 1:2:4 at 90 C. Subsequently the resulting polymers with active bromo end group structure were used as macroinitiators for the polymerization of the second monomer under the same condition. The triblock copolymers of BMA and St. EMA and St. MMA and BMA with predicted molecular weight (10000-50000) and narrow molecular weight distribution (1 .2-I .7) were obtained. It was found that St only could be used as the first monomer when methacrylate was copolymerized with St.A detail synthesis and purification process of chain transfer agent (CTA) dithioester (2-phenvlprop-2-yl dithiobenzoate and I -phenylethyl dithiobenzoate) was described. When the mole ratio of AIBN/CTA equals to 1:4, the RAPT polymerization had the character of livingpolymerization, indicated by the narrow polydispersity product (1 1-1.3) and a linear molecular weight-conversion profile, the predictability of the molecular weight from the ratio of monomer consumed to transfer agent and the ability to produce block copolymer by further monomer addition. A series of monomers: MMA, BMA, methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), and St were polymerized in bulk by Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. All of these homopolymers (PMMA, PBMA, PEA, PBA, PMA, PSt) had the control polymerization characteristics. At the same reaction condition, the rate of polymerization of methacrylate was the fastest. styrene was slower, acrylate was the slowest. The higher the reaction temperature, the faster the polymerization rate. It was discussed the effects of the mole ratio of chain transfer agent to initiator on polymerization and the effects of conversion and reaction time on the molecular weight and molecular weight distribution of the prepared block copolymers. These copolymers had the characteristics of the living free radical polymerization, that is to say that the real molecular weight of these copolymers were similar to the theoretical molecular weight, and the polydispersity index was less than 1.80. When the mole ratio of AIBN to CTA arranged from 1:3 to 1:6, the copolymers which first block was PSt also had characteristics of living radical polymerization product. The 'H NMR spectra of the homopolymer (PMMA) and copolymer (PMMA.-b--PEA) showed that the synthesized polymers had functional ground, dithioester, at the end of these polymers.BMA, BA and vinyl acetate (VAc) were polymerized by living radical polymerization in water using Reversible Addition-Fragmentation chain transfer (RAFT process). 1-phenylethyl dithiobenzoate (PhC(S)SCH(CH3)Ph) was selected as dithioester chain transfer agent, 2,2 '-azobis(2-cyanopropane)(AIBN) and ammoni urn peroxysulfate (APS) were used as initiator respectively. The best ratio of chain transfer agent to initiator for controllingpolymer molecular weight and narrow molecular weight distribution was 3.3-4.0. The living character of the RAFT process in water was also indicated by the narrow polydispersity product (1.l-1.3), a linear mo...
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