Thermoresponsive double-network hydrogel/elastomer hybrid bilayer laminates with high interfacial toughness and controllable shape deformations

Thermoresponsive hydrogel-based actuators have shown great potential in tissue engineering, biosensors and soft robots, while the preparation of temperature-driven bilayer hydrogel actuators with rapid responseness and recovery properties remains a challenge. Inspired by the layered heterostructure of human skin, we developed a Janus bilayer structure actuator consisting of thermoresponsive double network (TDN) hydrogel and polydimethylsiloxane (PDMS) elastomer with tough interface adhesion. Specifically, PNaAMPS/P(NIPAM-co-AAm) TDN hydrogel via photocopolymerization of N-isopropyl acrylamide (NIPAM) and acrylamide (AAm) and reinforced by microgel poly(2-acrylamide-2-methylpropane sulfonate sodium salt) (PNaAMPS) was in situ grafted onto benzophenone-activated PDMS surface, exhibiting strong interface adhesion (628 Jm-2 adhesion energy). The thermoresponsive shape deformations of the double-layer structure actuator were controllable by adjusting hydrogel/elastomer thickness ratio and introduction of metal ions, taking advantage of the different swelling and shrinkage characteristics of the hydrogel layer and the elastomer layer. The TDN/PDMS bilayer structure actuator, which integrates the Janus structure, thermal responsiveness and photothermal conversion, provides new ideas for the application and remote control of soft robots and soft actuators.

Automated summary

This study developed a thermoresponsive hydrogel-based actuator with a bilayer structure consisting of a thermoresponsive double network hydrogel and a polydimethylsiloxane elastomer. The shape deformations of the bilayer actuator were controllable by adjusting the thickness ratio of the hydrogel and elastomer layers and introducing metal ions.