Study Of SET-LRP Copolymerization

SET-LRP has shown its distinct advantages over other "living"/controlled radical polymerization (LRP) since its emergence in2006by Percec et al., including mild reaction conditions (room temperature or below), a catalytic amount of catalyst, ultrafast polymerization and resultant of high molecular weight polymers with low polydispersity. Furthermore, copolymerization is one of the most used methods in synthizing polymers in industry. For the advantages of SET-LRP and the importance of copolymerization in industry and research, it is of high interests to study SET-LRP copolymerization in. This thesis contains three work:(1) The LRP of Sty is rather slow at ambitient temperature. For its’rather slow polymerization rate and poor controle, there is no successful report about polymerization of Sty with SET-LRP mothod. In this work, SET-LRP copolymerization of methyl methacrylate (MMA) and styrene (Sty) was explored. The polymerization was carried out at25℃with N,N,N’,N",N"-pentamethyldiethylenetriamine as ligand and N,N-dimethylformamide as solvent. The copolymerization proceeded successfully while demonstrating characteristics of "living"/controlled radical polymerization. The copolymerization was confirmed as a random copolymerization. Based on1H NMR spectra, the reactivity ratios of MMA and Sty were calculated to be0.545and0.507, respectively. The solvent was found to have an important role on the copolymerization, with DMF giving a more controlled copolymerization than DMSO. The selected initiator should match both monomers for a good control over the copolymerization. Suitable concentration of Cu(0)/PMDETA should be used to balance the polymerization rate with polymerization controllability.(2) The LRP of vinyl acetate (VAc) is still a challenge due to its unconjugated duble bond. The SET-LRP of VAc has a extremly low rate and a poor control. In this work, SET-LRP copolymerization of VAc and acrylonitrile (AN) was explored. The copolymerization proceeded successfully while demonstrating characteristics of controlled/living radical polymerization at25℃. The result confirmed that the composition of the copolymer depended on the monomer feed, not on the conversion. The reactivity ratios of VAc and AN were calculated to be1.605and0.003in the system, respectively. Therefore, copolymers of VAc and AN with predetermined composition and molecular weight can be realized via SET-LRP.(3) Since that the repeat unit sequence has crucial effects on copolymer properties, the research of precise sequences control is one of the research hot topic in present researches. In this work, we studied the copolymerization of MMA and AN. The results demonstrated that the polymerization was "living"/controlled. Importantly, the different monomer feed played a key role in copolymer sequences. The best mole ratio for preparing MMA/AN gradient copolymer was revealed as1/2of MMA to AN via SET-LRP at room temperature.