Fast-response photothermal bilayer actuator based on poly(N-isopropylacrylamide)–graphene oxide–hydroxyethyl methacrylate/polydimethylsiloxane

Demands for highly deformable and responsive intelligent actuators are increasing rapidly. Herein, a photothermal bilayer actuator consisting of a photothermal-responsive composite hydrogel layer and a polydimethylsiloxane (PDMS) layer is presented. The photothermal-responsive composite hydrogel is prepared by compositing hydroxyethyl methacrylate (HEMA) and the photothermal material graphene oxide (GO) with the thermal-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAM). The HEMA improves the transport efficiency of water molecules inside the hydrogel network, eliciting a fast response and large deformation, facilitating greater bending behavior of the bilayer actuator, and improving the mechanical and tensile properties of the hydrogel. Moreover, GO enhances the mechanical properties and the photothermal conversion efficiency of the hydrogel in the thermal environment. This photothermal bilayer actuator can be driven under various conditions, such as hot solution, simulated sunlight, and laser, and can achieve large bending deformation with desirable tensile properties, broadening the application conditions for bilayer actuators, such as artificial muscles, bionic actuators, and soft robotics.