Multi-stimuli responsive bilayer film based on clay and graphene derivative for flexible and smart devices

Abstract

Designing a smart actuator with multi-response behaviors is highly demanded for the development of intelligent systems by using low-cost materials and facile fabricating method. Herein, the bilayer actuators with controlled and large deformation, were prepared with montmorillonite (Mt), graphene oxide (GO) and their derivatives (organic montmorillonite (OMt) and reduced graphene oxide (rGO)) by simple casting method. The prepared bilayer films with periodic microchannel patterns consist of hydrophilic GO-Mt layer and hydrophobic rGO-OMt layer, exhibiting good actuating performance under the external stimuli of humidity, organic solvent and infrared (IR) light. With the increase of rGO/OMt ratio, the humidity-triggered bending angle of the bilayer films increases, but the humidity-triggered deformation changes from reversible bending to irreversible state. Remarkably, different from the bending direction toward rGO-OMt side in humid environment, the bending in opposite directions toward GO-Mt side is observed in response to organic solvent and IR light. The bilayer films show reversibly bidirectional bending under the alternating stimuli of humidity/organic solvent or humidity/IR light. These bilayer films were tailored to fabricate the programmable actuators, which were successfully applied as smart switches, smart windmills, bioinspired blooming flowers, flapping wings of paper cranes and predatory tongue of frogs. This work provides a potential pathway for the development of low-cost multi-responsive materials for more versatile applications in various smart devices.