In Situ Electric-Induced Switchable Transparency and Wettability on Laser-Ablated Bioinspired Paraffin-Impregnated Slippery Surfaces

Abstract

Switchable wetting and optical properties on a surface is synergistically realized by mechanical or temperature stimulus. Unfortunately, in situ controllable wettability together with programmable transparency on 2D/3D surfaces is rarely explored. Herein, Joule-heat-responsive paraffin-impregnated slippery surface (JR-PISS) is reported by the incorporation of lubricant paraffin, superhydrophobic micropillar-arrayed elastomeric membrane, and embedded transparent silver nanowire thin-film heater. Owing to its good flexibility, in situ controllable locomotion for diverse liquids on planar/curved JR-PISS is unfolded by alternately applying/discharging low electric-trigger of 6 V. Simultaneously, optical visibility can be reversibly converted between opaque and transparent modes. The switching principle is that in the presence of Joule-heat, solid paraffin would be melt and swell within 20 s to enable a slippery surface for decreasing light scattering and frictional force derived from contact angle hysteresis (FCAH). Once Joule-heat is discharged, undulating rough surface would reconfigure by cold-shrinkage of paraffin within 8 s to render light blockage and high FCAH. Upon its portable merit, in situ thermal management, programmable visibility, as well as steering functionalized droplets by electric-activated JR-PISSs are successfully deployed. Compared with previous Nepenthes-inspired slippery surfaces, the current JR-PISS is more competent for in situ harnessing optical and wetting properties on-demand.