Near-infrared light accurately controllable superhydrophobic surface from water sticking to repelling

Abstract

Great attention has been paid to superhydrophobic surface with tunable water adhesion behaviors, but many challenges still remain for developing a surface with accurate regional control of the superwetting behaviors to realize on-demand responses. Herein, a superhydrophobic surface with accurately controllable water adhesion performance for local areas has been developed, by integrating carbonyl iron particles (CIPs) into a shape memory polymer (SMP) to get photothermal-responsive pillar array. The morphologies of the programmed surface can be remotely and accurately regulated through near-infrared (NIR) light irradiation, hence resulting in the accurate control of surface superwetting behaviors. By adjusting the intensity and targeted area of the NIR irradiation, the controllable surface deformation even in a minimal area of ~0.95 mm2 can be achieved. Among those, the surface with bent microstructures demonstrates high water adhesion force (98 μN) with a high water rolling-off angle (even the surface was overturned to 180°), whereas the superhydrophobic surface with the recovered micro/nanostructure arrays exhibits relatively low water adhesion force (25 μN) with an extremely low rolling-off angle (4°). We have proven that these programmable superhydrophobic surfaces can not only accurately adjust the droplet adhesive force in the target area, but also serve as ideal platforms for distinct microfluidic microreactors. These unique characteristics endow the NIR light remotely controlled superhydrophobic surfaces with special advantages for abroad applications in liquid droplet manipulations, micro reactions, biochemical detections, etc.