原子转移自由基聚合法制备聚乳酸三嵌段共聚物的研究

Synthesis of polylactide block copolymer by atom transfer radical polymerization

以自制的双端羟基聚乳酸与α-溴代丙酰溴反应而制得的含溴端基的聚乳酸为大分子引发剂,溴化亚铜/2,2′-联吡啶为催化体系,研究了N-乙烯基吡咯烷酮的原子转移自由基聚合行为,制得了具有两亲性聚乳酸嵌段共聚物。随单体/引发剂摩尔比的增大、聚合温度的升高,共聚物溶液的特性黏度增大,共聚物薄膜的吸水率增加;共聚物在不同降解介质中的降解规律相似,均随降解时间的延长,共聚物薄膜的失重增加,且在不同介质中呈现的降解速率表现为碱液>酸液>水>缓冲液。对聚合物进行了结构表征。

An amphiphilic block copolymer of poly（N-vinylpyrrolidone） and polylactide was synthesized by the atom transfer radical polymerization （ATRP） using N-vinylpyrrolidone as the monomer and polylactide containing α-bromoester group as the macromolecular initiator with CuBr/2, 2＇-bipyridine as the catalyst system. The viscosity and the water uptake of polylactide copolymer increased with raising reaction temperature and increasing mole ratio of monomer to macromolecular initiator. Their degradation behaviors in phosphate buffer solution （pH 7.4）, water, NaOH or HCl solution at 37℃ were investigated in detail by monitoring the changes in mass during the degradation. The target copolymers degraded rapidly; and the higher of PVP content, the faster the copolymer degraded; degradation of copolymer in NaOH solution was more rapid than others. The characterization of the copolymer was also made.