聚丙交酯——聚乙二醇嵌段共聚物的合成与性能研究

采用两段反应,先通过辛酸亚锡催化低分子量端羟基聚乙二醇(PEG)(数均分子量1000和2000)与L-丙交酯(L-LA)的开环聚合合成含有端羟基的低分子量聚丙交酯--聚乙二醇-聚丙交酯(PLA-PEG-PLA)三嵌段低聚物,再用六亚甲基二异氰酸酯(HDI)进行扩链反应合成了一系列不同力学性能的聚丙交酯--聚乙二醇(PLA-PEG)多嵌段共聚物.确定了扩链过程中,多嵌段共聚物膜达到最佳力学性能的反应条件.采用X射线衍射及DSC分析表征了聚合物的结晶结构与熔融温度的变化,发现随PEG含量的增加,聚合物的结晶性与熔融温度均下降.对聚合物膜的吸水性及降解性的测试结果表明,PEG分子量相同时,PEG含量增加,聚合物膜吸水性增强,降解速度加快;同组分比例的PEG2000-PLA多嵌段共聚物的吸水性及降解性均比PEG1000-PLA多嵌段共聚物强.

Study on synthesis and properties of poly (L -lactide) -poly (ethylene glycol) block copolymers

The OH-terminated PLA-PEG-PLA triblock copolymers were synthesized by the ring-opening polymerization of L-lactide(L-LA)and the low molecular weight(Mw=1000 or 2000) poly(ethylene glycol)(PEG),using the stannous octanoate as the catalyst.And then using hexamethylene diisocyanate(HDI) as chain extender,a series of PLA-PEG multiblock copolymers with different mechanical property were synthesized.The optimum conditions in the reaction of chain extension were determined to produce the PLA-PEG multiblock copolymers films with the best mechanical property.The crystallization structures and melting temperature were characterized by X-ray diffraction analysis and DSC thermogram analysis.Water absorption and degradation were tested.The results show that with PEG increasing,the crystallizibility and melting temperature were decreased,and water absorption was enhanced and degradation was quickened.As far as the same composition was concerned,PLA-PEG2000 multiblock copolymers films had better properties of water absorption and degradation than PLA-PEG1000 multiblock copolymers films.