On-Demand Shape Recovery Kinetics Modulation with a Wide Regulation Range and Spatially Heterogeneous Shape Recovery Rate

Abstract

A suitable deformation rate is crucial for shape memory polymers (SMPs) in real word applications. Yet on-demand modulation in shape recovery kinetics and its spatial heterogeneous control still need to be explored systematically. Herein, a near-infrared (NIR) light controlling strategy was demonstrated for in situ modulation in both shape recovery rate and its spatial heterogeneity. Polyvinyl alcohol and chitosan, two typical SMPs, were chosen to elaborate the strategy, due to their heat-responsive shape memory effect (SME) and chemoresponsive SME, respectively. Reduced graphene oxide was incorporated in the SMPs to endow them with NIR light controllability. Through light intensity adjustment, the shape recovery rate could be altered by nearly an order of magnitude without any modification of material composition. Similar shape transition kinetics at different ambient temperatures could be achieved. More impressively, spatially modulated recovery kinetics was successfully conducted to avoid undesired self-collisions or self-interferences in complex shape shifting processes and thus prevent possible shape transition failure. As the regulatory information was not encoded in the SMPs, deformation rate and its spatial differentiation could be adjusted flexibly after material preparation, allowing the adaptability of the shape shifting process under conditions with individual differences.