A temperature‐responsive dual network hydrogel for reversible smart actuator

Nowadays, soft actuators have received extensive attention in many application fields, among which hydrogels have become an important choice for constructing soft actuators due to their unique properties. However, the actuating behaviors of hydrogel‐based actuators are usually monotonous due to their unchangeable shapes and structures. Herein, we report a temperature‐responsive hydrogel actuator with a bilayer structure. Based on the dual network structure (polyvinyl alcohol/poly acrylamide and polyvinyl alcohol/poly (N‐isopropylacrylamide), the actuators can realize the reinforcement compared with the single network. Because of the intrinsic lower critical solution temperature of poly (N‐isopropylacrylamide, both sides of actuators have different swelling rates, enabling them to achieve the thermal‐responsive actuation and shape programming. Therefore, this work is promising to provide a new strategy for designing temperature switches and thermally driven soft robots. Schematic illustration of temperature‐responsive dual network hydrogels and the hydrogel‐based actuators.