The robustness of superhydrophobicity is a fundamental issue for the applications of water‐repellent materials. Inspired by the hierarchical structures of water‐strider legs, this work describes a new water‐repellent material decorated with ribbed, conical nanoneedles, successfully achieved on the surface of copper and consisting of copper hydroxide nanoneedle arrays sculptured with nanogrooves. The behavior of water drops on an as‐prepared surface under various external disturbances is investigated. It is shown in particular that squeezing and relaxing drops between two such surfaces leads to a fully reversible exploration of the solid surface by the liquid, which is distinct from other superhydrophobic surfaces. This unique character is attributed to the penetrating Cassie state that occurs at the ribbed, conical nanoneedles. The proprietary lateral nanogrooves can, not only vigorously support the enwrapped liquid‐air interface when a force is applied to the drop, but also provide reliable contact lines for the easy de‐pinning of the deformed interface when the force is released from the drop. The results confirm the exceptional ability of strider legs to repel water, and should help to further the design of robust water‐repellent materials and miniaturized aquatic devices.

Surface-wettability response has been intensively studied under external stimulus such as light irradiation, [1][2][3][4][5] electric fields, [6][7][8][9][10][11][12] thermal treatment, [13] pH, [14,15] and solvent treatment. [16] Specially, the cooperation of different stimuli (e.g., optoelectrowetting) seems to be a trend for more effective surface wetting. [17] Despite much progress in this field, the precise controllable patterned wetting is still a challenge. Here, we report an approach to address the precise controllable patterned wettability transition on the superhydrophobic aligned photoconductive nanorod-array surface via a photoelectric cooperative wetting process. Namely, applying a bias lower than the electrowetting threshold voltage, photoelectric cooperative wetting can be realized only at the illumination site, that is, the patterned site. This work is promising to gear up the application of locally confining liquid at a desired location, such as liquid reprography by patterned light illumination.In order to realize the patterned photoelectric cooperative wetting, photoconductive materials and special surface structure with anisotropic wetting are necessary. [18,19] Aligned-ZnOnanorod array is an ideal candicate to achieve this purpose, because ZnO is a wide-band-gap semiconductor and its aligned-nanorod array can exhibit anisotropic wetting under illumination, that is, wetting easily occurs in the direction parallel to the nanorods due to the capillary effect, while it is difficult in the direction vertical to the nanorods due to the discontinuous three-phase contact line. [19][20][21][22][23] In this study, the aligned-ZnOnanorod array is first grown perpendicularly onto the substrate, and then coated with titanyl phthalocyanine (TiOPc) as a composite photoconductor layer. Finally, the TiOPc-coated ZnO nanorod array is modified by heptadecafluorodecyltrimethoxysilane (FAS) to improve the surface hydrophobicity. Figure 1 shows the scanning electron microscopy (SEM) images, water-contact angle (CA) photographs, and schematic diagrams of the as-prepared aligned-ZnO-nanorod arrays. The top-view SEM images indicate that before (Fig. 1a) and after (Fig. 1b) the ZnO nanorods were coated with TiOPc and then after they were modified by FAS (Fig. 1c), their morphologies did not change significantly, while the average diameter increased from (81.9 AE 26.8) to (185.2 AE 21.6) and (198.3 AE 31.6) nm, respectively, and the final average spacing between composite nanorods becomes (156.4 AE 25.3) nm. The side-view SEM images indicate that the nanorods are grown almost perpendicularly onto the substrate with a length of %3 mm. As confirmed by the X-ray diffraction (XRD) pattern with a remarkable (002) peak (see Fig. S1a-c in Supporting Information), the surface of the films is the (001) plane of the nanorods. As a result, the as-prepared aligned composite nanorod-array (ACNA) surface is turned to a superhydrophobic surface with a CA of (158.48 AE 1

Biomimetic asymmetric nanochannels have recently attracted increasing attention from researchers, especially in the aspect of the asymmetric wettability (a hydrophilic-hydrophobic system), which can be utilized to control the wetting behavior of aqueous media and to offer a means for guiding water motion. By using molecular dynamics simulations, a design for a potentially efficient water filter is presented based on (n, n) single-walled carbon nanotubes, where n = 6, 8, 10 and 12, asymmetrically modified with hydrophilic groups (carboxyl, -COOH) at one tip and hydrophobic groups (trifluoromethyl, -CF(3) ) at the other. The reduced water density on the hydrophobic sides of the functionalized nanotubes are observed in both pure water and aqueous electrolyte solution, except for the functionalized (6, 6) tube, due to the change of dipole orientation of the single-file water wire within it. The functionalized (8, 8) tube can significantly maintain the low water density on the hydrophobic side. Both (6, 6) and (8, 8) tubes have relatively high energy barriers at their tips for ion permeation, which can be obtained by calculating the potential of mean force. Such tip functionalization of a nanotube therefore suggests the great possibilities of water transport and filtration, dominated by asymmetric wettability. The functionalized (8, 8) tube could act as a nanofluidic channel for water purification, not only for ion exclusion but also as a stable water column structure.