Semicrystalline polymer networks with a swelling-enhanced water-triggered two-way shape-memory effect for programmable deformation and smart actuation

Abstract

Two-way shape-memory polymers (2W-SMPs) have gained much attention due to their great potential in smart actuators, soft robotics, and artificial muscles. However, the application of 2W-SMPs is always limited by the complex fabrication process and strict triggering conditions. In this work, we propose that water-triggered 2W-SMPs can be facilely fabricated by one-step free radical polymerization of vinyl-ended 6-arm poly(ethylene glycol)-poly(ε-caprolactone) and vinyl-ended Pluronic F127. The crosslinked networks show a programmable and reversible water-triggered two-way shape-memory effect (2W-SME) based on two independent crystalline domains, with the highest angle reversibility of 45.2%. Due to the asymmetrical swelling induced by the asymmetrical cross-section chemical structure formed in the fabrication process, spontaneous bending behavior is observed, further enhancing the 2W-SME. In addition, the networks with 60% Pluronic F127 can be applied as a soft gripper and water level monitor, which exhibits programmable deformation. Therefore, a convenient and effective strategy is proposed to fabricate 2W-SMPs, which can be extended to other polymers to obtain water-triggered 2W-SMPs.