Synergistic water-driven shape memory performance and improving mechanism of grading photo-thermal curing shape memory composite

Shape memory materials draw much attention due to various promising potential applications. This work prepares a novel shape memory composite via grading photo-thermal curing method, which has not yet been reported. Expectedly, it merges advantages of epoxy-based shape memory polymer (EP) and polyvinyl alcohol-based shape memory polymer (PVA), which has applicable stiffness and multi-stimuli responsive performance. The unsatisfactory mechanical properties of most water-driven shape memory polymer (SMP) is expected to be solved by this fabrication strategy, so that the application range of water-driven SMP could be further extended. The synergistic plasticization of PVA and EP dominates water-driven shape memory behavior of this composite. Interestingly, its water-driven shape memory performance is able to be further improved by immersed in HCl/EtOH solution. The glassy-to-rubbery modulus ratio (E′g/E′r) of the PVA/EP-HCl/EtOH is about 650 after immersed in 0.1 mol/L HCl/EtOH for 6 h. In addition, this immersed method also can solve the post curing problem of such cationic photocuring. It is an easy, efficient, economical strategy for improving synergistic water-driven shape memory performance. Furthermore, this shape memory composite is expected to provide new perspective and practical approach to realize the intellectualization of underwater deployment and release structure.