Stereospecific Living Radical Polymerization and Synthesis of Stereoblock Polymers

本研究旨在将活性自由基聚合和立体特异性自由基聚合有效地结合起来，以同时控制分子量和分子量，从而发展立体特异性活性自由基聚合。成功的关键是找到适当的组合，其中一个控件不应该被另一个组件丢失。我们发现几种组合诱导了各种单体的立体特异性活性自由基聚合，如甲基丙烯酸酯、丙烯酰胺、醋酸乙烯和n -乙烯基吡咯烷酮。下面是对每个系统的总结。(1)钌催化甲基丙烯酸酯在氟醇和非质子溶剂中的活性自由基聚合甲基丙烯酸甲酯与Ru(Cp^*)Cl(PPh_3)_2在（CF_3）_3COH中聚合，得到窄分子量分布（MWDs）和高共异性的聚合物（M_w/M_n=1.07, r=88%）。在Ru(Cp^*)Cl(PPh_3)_2存在下，DMF作为溶剂诱导了共异活自由基聚合。通过聚合得到了立体嵌段聚合物。(2)铁催化丙烯酰胺在金属三平面存在下的活性自由基聚合，n-二甲基丙烯酰胺在Y(OTf)_3存在下与[FeCp(CO)_2]_2聚合，得到分子量可控、等规性高的聚合物（M_w/M_n=1.87, m=82%）。(3)醋酸乙烯酯在氟醇中的碘-转移自由基聚合，在m-C_6H_4{C(CF_3)_2OH}_2中进行了醋酸乙烯酯的碘-转移自由基聚合，得到了较窄的MWDs和较高的共异性聚合物（M_W/M_n=1.20, r=59%）。(4)利用黄药介导的n -乙烯基吡咯烷酮在氟醇酸盐中自由基聚合，对n -乙烯基吡咯烷酮在（CF_3）_3COH中自由基聚合的分子量进行控制，得到分子量可控且高共异特异性的聚合物（M w/M_n=1.28, r=60%）。

This research is directed to developing the stereospecific living radical polymerization by effectively combining the living and stereospecific radical polymerizations for the simultaneous control of the molecular weights and tacticity. The key to the success is to find appropriate combinations where one of the controls should not be lost by the other component. We found that several combinations induced stereospecific living radical polymerizations of various monomers such as methacrylates, acrylamides, vinyl acetate, and N-vinylpyrrolidone. The followings summarize each system.(1) Ruthenium-catalyzed living radical polymerizations of methacrylates in fluoroalcohols and aprotic solventsMethyl methacrylate was polymerized with Ru(Cp^*)Cl(PPh_3)_2 in (CF_3)_3COH to give polymers with narrow molecular weight distributions (MWDs) and high syndiotacticity (M_w/M_n=1.07, r=88%). For the polymerization of 2-hydroxyethyl methacrylate, DMF as a solvent induced syndiospecific living radical polymerization in the presence of Ru(Cp^*)Cl(PPh_3)_2. By using the polymerizations, stereoblock polymers were obtained.(2) Iron-catalyzed living radical polymerizations of acrylamides in the presence of metal triflatesN,N-Dimethylacrylamide was polymerized with [FeCp(CO)_2]_2 in the presence of Y(OTf)_3 to result in the polymers with controlled molecular weights and high isotacticity (M_w/M_n=1.87, m=82%).(3) Iodine-transfer radical polymerizations of vinyl acetate in fluoroalcoholsIodine-transfer radical polymerization of vinyl acetate was done in m-C_6H_4{C(CF_3)_2OH}_2 to result in the polymers with narrow MWDs and relatively high syndiotacticity (M_W/M_n=1.20, r=59%).(4) Xanthate-mediated radical polymerizations of N-vinylpyrrolidone in fluoroalcoholsXanthate was employed for the control of molecular weight in radical polymerization of N-vinylpyrrolidone in (CF_3)_3COH to result in the polymer with controlled molecular weights and high syndiospecificity (M w/M_n=1.28, r=60%).