Preparation of thermally and chemically robust superhydrophobic coating from liquid phase deposition and low voltage reversible electrowetting

Superhydrophobic surfaces and electrowetting have found applications in many fields. Two of the most desired features in these applications are a robust surface and low voltage actuation electrowetting. A thermally and chemically robust nano-scale superhydrophobic surface was prepared using facile techniques of sol-gel and hot water treatment to obtain rough pseudoboehmite alumina structures; and layer-by-layer coating, using Nafion®, to achieve the hydrophobization. It exhibited a contact angle of 167.2 ± 0.8°; thermal stability of up to 300 °C; stability to acid, base, organic solvents and UV irradiation. Subsequently replacing Nafion® with 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane and a conductive Au under layer coating, an extremely low voltage, 3 V, electrowetting and reversible electrowetting were achieved in air and dodecane media, respectively.