Superfast, Porous, and Organic Solvent-Sensitive Actuator Based on EVOH Nanofibrous Membrane and PS Microspheres

Despite much progress in solvent-sensitive actuators, most of the actuators are sensitive to water, ethanol, or acetone with low responsive speed and small curvature. Herein, a simple approach was introduced to fabricate a new solvent-sensitive bilayer actuator consisting of a poly­(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membrane and polystyrene (PS) microspheres. The actuator showed superfast and multistimulus responsive ability to organic vapors of toluene, chloroform, THF, and acetone. With solvents stimulation, the difference in swelling degree between the EVOH layer and PS microspheres layer contributed to the asymmetric expansions or contractions of two layers, therefore resulting in the mechanical deformation of the actuator. The flexible and porous EVOH nanofibrous membrane, as well as the spherical PS, could improve the response rate and deformation scale. This bilayer actuator could bend quickly into a multicoil with the curvature of 21.02 cm–1 within 0.15 s in response to toluene vapor, and the bending–unbending process could repeat more than 150 times when the deformation degree was controlled by cross-linking PS microspheres with divinylbenzene. This study will provide an important insight for the development of new solvent-sensitive devices and applications in volatile organic compounds detecting.