苯乙烯原子转移自由基聚合及其嵌段共聚物合成

Atom transfer radical polymerization of styrene and synthesis of its block copolymer

分别采用氯乙酸甲酯、氯乙腈、氯化苄和三氯乙酸甲酯作引发剂，氯化亚铜／２，２′联吡啶配位化合物作催化剂，进行了苯乙烯（Ｓｔ）和甲基丙烯酸甲酯（ＭＭＡ）的原子转移自由基聚合，研究了引发剂种类对聚合速率及所得聚合物的相对分子质量及其分布的影响，并考察了各种引发剂的引发效率。实验结果表明，只有当引发剂Ｃ—Ｃｌ键断裂能低于聚合物末端Ｃ—Ｃｌ键断裂能时，才能得到较高的引发效率，聚合物的相对分子质量分布也较窄。另外，还以氯乙腈引发得到的聚苯乙烯作为大分子引发剂进行了丙烯酸甲酯、乙酯和丁酯的原子转移自由基聚合，得到了ＡＢ型嵌段共聚物，而对于ＭＭＡ，引发效率较低，只有部分聚苯乙烯引发ＭＭＡ聚合生成了嵌段共聚物。

The atom transfer radical polymerization of styrene(St) and methyl methacrylate(MMA) initiated by methyl chloroacetate (MCA), chloroacetonitrile(CAN), benzyl chloride(BC) and methyl trichloroacetate(MTCA) in the presence of CuCl(Ⅰ)/2,2′ bipyridine complex was investigated. When CAN and MTCA were used as initiators, the polymerization rate was fast, the initiating efficiency was high and the molecular weight distribution (MWD) was narrow. While MAC and BC were used as initiators, the polymerization rate was slower, the initiating efficiency was lower and the MWD was broader. Additionally, sequential atom transfer radical living polymerization of alkyl (meth)acrylate from PS with CAN as initiator afforded AB type block copolymers. The MWD of poly(styrene b alkyl acrylate) was narrow(same as PSt), but the MWD of poly(St b MMA) copolymer was very broad and had two peaks. The above results were interpreted according to the difference of C—Cl bond dissociation energy between initiator and polymer.