聚L-乳酸/聚ε-己内酯嵌段共聚物的形状记忆效应

Shape memory effect of poly(L-lactide)/poly(ε-caprolactone)block copolymer

采用两步法合成聚L-乳酸/聚ε-己内酯(PCLA)嵌段共聚物,并通过红外光谱(FTIR)和凝胶渗透色谱(GPC)方法加以表征。采用差示扫描量热分析(DSC)、X射线衍射分析(XRD)和拉伸试验对PCLA嵌段共聚物的微观结构和形状记忆效应进行了系统的研究。研究结果表明PCLA嵌段共聚物中聚L-乳酸(PLLA)和聚ε-己内酯(PCL)链段可以单独结晶,共聚物中存在PLLA和PCL两种结晶相。同时,PCLA嵌段共聚物具有优异的形状记忆效应,其中PLLA结晶相作为物理交联点,PCL链段及PLLA无定型相作为可逆相。在变形量为200%时,获得最大的形状恢复率超过90%,恢复力接近4MPa。

The poly（L-lactide）/poly （ε-caprolactone） （PCLA） block copolymer was synthesized by two step method and the characterization was carried out by fourier transform infrared spectrum （FTIR） and gel permeation chromatography （GPC）. The microstructure and shape memory effect were investigated systematically by using differential scanning calorimetry （DSC）, X-ray diffraction （XRD） and tensile test, respectively. The experimental results show that the PLLA and PCL chain segment can crystallize separately, and there are two crystal domains in the block copolymer. Meanwhile, the PCLA block copolymer exhibits superior shape memory effect. The PLLA crystal serves as fixed phase, while the PCL and amorphous PLLA chain segment act as reversible phase. The shape recovery rate exceeds 90% and recovery stress is close to 4MPa when the deformation strain is 200%.