Regulating Water Adhesion on Superhydrophobic TiO₂ Nanotube Arrays

Bioinspired surfaces with special wettability have attracted a significant attention in recent years because of their potential applications for no loss liquid transfer, anti‐icing, and self‐cleaning. Herein, the realization of two extreme superhydrophobic states on 1H, 1H, 2H, 2H–perfluorooctyltriethoxysilane‐modified TiO 2 nanotube arrays (NTAs) is described by changing the structural characteristics of nanotubes while keeping the surface chemical composition constant. The water adhesive force is regulated in a wide range from ≈4.4 to ≈89.6 μN by the nanotubular diameter, length, density, and surface roughness. The cooperation effect between the negative pressures induced by the volume change of sealed air‐pockets and the van der Waals' attraction at solid–liquid interface contributes to the water adhesion. The superhydrophobic TiO 2 NTAs with a high adhesive force is used as a “mechanical hand” to transfer water microdroplets without any loss, and the one with extremely low adhesive force is utilized as a self‐cleaning and anti‐icing surface.