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

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 4 MPa when the deformation strain is 200%.