Stress‐Free Two‐Way Shape Memory Polymers with Dual‐Crystalline Phase Based on Poly(Tetramethylene Ether Glycol) and Poly(<i>ε</i>‐Caprolactone)

Abstract

Abstract Two‐way shape memory polymers (2W‐SMPs) are a class of smart materials and can undergo spontaneously reversible deformation after specific stimuli. It is crucial to develop 2W‐SMPs to achieve precise control of two‐way shape memory behavior without external forces and reveal their structure‐property relationships. In this study, dual‐crystalline phase crosslinked polymer networks based on poly(tetramethylene ether glycol) (PTMEG) and poly(ε‐caprolactone) (PCL) are fabricated via thiol‐ene click reactions. The networks with two independent melting temperatures are gained by adjusting the ratio of the two segments and the two‐way shape memory is enabled using the temperature difference between the two phases. The effects of network composition, pre‐tensile strain, and actuation temperature on the two‐way shape memory properties are investigated and the two‐way shape memory mechanism of dual‐crystalline phase polymers is further elucidated. Among the various compositions of networks, PTMEG 8 ‐PCL 2 exhibits the optimal two‐way shape memory properties, with the actuation strain of 24.25% and reversible strain of up to 10.35% at the actuation temperature and pre‐stretch strain of 45 °C and 15%, respectively, which is potential for soft robotics applications. It is believed that this work guides the design of semicrystalline networks with two‐way shape memory properties.