熔融缩聚合成聚乳酸-聚乙二醇共聚物及其性能研究

采用羧基封端乳酸预聚物与聚乙二醇熔融缩聚合成了聚乳酸-聚乙二醇共聚物,并用GPC、FTIR、1H-NMR等方法表征了预聚物与共聚物,结果表明,预聚物的羧基封端率高于95%,预聚物的相对分子质量可由投料比(物质的量比)控制.热分析结果表明,共聚物中聚乳酸链段呈无规分布,而聚乙二醇链段能够形成结晶微区.力学性能测试结果表明,共聚物的断裂伸长率达371%,有望在聚乳酸韧性改性方面得到应用.

Synthesis and Properties of Poly(L-lactic acid)/Poly(ethylene glycol) Copolymers

Poly(L-lactic acid)-poly(ethylene glycol)(PLA-PEG)copolymers are synthesized by the melt copolycondensation of poly(ethylene glycol)(PEG) and carboxyl terminated lactic acid prepolymer. The chemical compositions of the prepolymers and copolymers are characterized by 1 H-NMR and FT-IR, the molecular weight and distribution are measured by GPC. The results show that the yield of termination of prepolymers is above 950%, and the molecular weight of prepolymers can be controlled by the feed ratio of L-lactic acid to succinic acid. DSC thermogram demonstrates that PLLA segments in copolymers distributes randomly, while PEG segments can form crystalline micro-domains. According to the tensile test,the breaking elongation rate of copolymer reaches 371% ,which indicates that the copolymer can be used to improve the impact strength of PLA.