Stimuli-responsive superhydrophobic films driven by solvent vapor for electric switch and liquid manipulation

Abstract

Fabrication of functional superhydrophobic materials with stimuli-responsive driving ability for the growing fields such as electric switch and liquid manipulation still remains mysterious and challenging. In this work, a stimuli-responsive superhydrophobic film (SSF) is fabricated by integrating a bottom porous poly(vinylidene fluoride) (PVDF) layer, a sandwiched cross-linkable poly(vinyl alcohol) (cPVA) layer, and a top carbon nanotubes@polydimethylsiloxane (CNTs@PDMS) layer. Induced by the asymmetric swelling of cPVA/PVDF bilayer upon exposure to acetone vapor, the SSFs directionally roll towards the superhydrophobic CNTs@PDMS surface with a large curvature of 0.65 mm−1, a fast response within 10 s, and an excellent fatigue resistance of more than 1000 actuation cycles. Furthermore, the special superhydrophobicity highly ensures the reliable actuation behavior of the SSFs under wet environments. Taking advantage of the conductivity of the CNTs@PDMS layer, the SSF-based electric switches are fabricated and conveniently actuated to control the electric circuit states of turning on/off. Additionally, thanks to the combination of water repellency and acetone vapor-responsive actuation, the SSFs are designed as smart channels for a water control system to successfully achieve the manipulation of liquid flow direction. The findings conceivably stand out as a new methodology to fabricate functional superhydrophobic materials with stimuli-responsiveness for various potential applications.