A facile approach to fabricate two-way shape memory polyurethane with large reversible strain and high shape stability

Because of their unique properties, shape memory polymers (SMPs) have the potential to be used in various fields and are becoming one of the most desired shape memory materials. At present, it is generally complicated to prepare the two-way shape memory polymers (2W-SMPs) with both large reversible strain and high shape stability, which has hindered the real applications. By elaborately selecting poly(e-caprolactone) diols (PCL-2OH) and poly(e-caprolactone) triols (PCL-3OH) as prepolymers, a facile one-step method is employed to prepare two-way shape memory polyurethane (2W-SMPU). For this kind of SMPU, the reversible strain is found to be closely related to both the mass ratio of PCL-2OH to PCL-3OH and the initial applied stress. In this work, the smart devices of temperature-controlled lamp and gripper based on 2W-SMPU are designed and fabricated to show its two-way shape memory effect (2W-SME). The results show that its largest reversible strain can be as high as 21.3%. Moreover, it can lift up 150 times of its own weight and keep an almost constant reversible strain under a temperature-induced actuation within 50 consecutive cycles. Such 2W-SMPU materials could have lots of real applications.