Light and solvent-driven actuator of clay and vanadium pentoxide nanosheets

Abstract

As the demand for advanced technological materials continues to rise, the lookout for materials capable of responding to external stimuli, such as heat, light, and chemical vapor, by changing their own shape and size is becoming increasingly important. Here, we report a novel light and vapor-responsive material prepared by a sequential assembly of exfoliated two-dimensional (2D) sheets of vermiculite and vanadium pentoxide (V₂O₅). Nanosheets of V₂O₅ are prepared by treating bulk V₂O₅ powder with H₂O₂ and those of vermiculite are obtained by stirring the bulk crystals in an HCl solution. The bilayer membrane of V₂O₅ and vermiculite displays outstanding shape-morphing characteristics upon exposure to light. The infrared light (IR) induced higher bending and recovery speeds (20.5° s⁻¹ and 8.2° s⁻¹) as compared to the white light (9.3° s⁻¹ and 6.4° s⁻¹). Unequal changes to the mechanical properties at the two sides of the bilayer membrane due to dissimilar light-induced heating are attributed to the shape-morphing characteristics. The light-induced bending movement of this bilayer membrane is also utilized to translocate objects from one place to another. Additionally, the bilayer membrane also responds to the presence of solvent vapors like 2-propanol, ethanol, methanol, ethyl acetate, dichloromethane (DCM), and acetone vapor by morphing its shape in a specific manner.