No abstract

The development of a unique multilayer detached superhydrophobic structure inspired by biology with excellent superhydrophobic properties, extremely short rebound time, and low surface free energy has become a challenging issue. In this work, a superhydrophobic coating is prepared on the surface of Al 1060 via a fluorine-free, efficient, economical, and environmentfriendly approach. First, a Ni nanocone layer is obtained from a recyclable electrodeposition solution. Then, stearic acid is prepared on the Ni nanocone layer by dip-coating technology, resulting in a special superhydrophobic surface called the "trampoline" structure, which is quite different from the Ni nanocone structure, as the substrate. The contact angle of water is 161.3°, and the sliding angle is 7°. In addition, the superhydrophobic coating with this special structure has had great achievement in adhesion work, resilience performance, porosity, corrosion resistance, and self-cleaning and antifouling performance. So far, very few reports have analyzed the performance of this special structure. To explain the bounce performance induced by this special trampoline structure, a multidimensional superhydrophobic bouncing mechanism was proposed. Furthermore, this work is expected to provide inspiration for future applications of the unique nonfluorinated trampoline structure in superhydrophobic materials.

No abstract

It is urgent and significant for the further development of superhydrophobic materials to exploit a facile, low-cost, scalable, and eco-friendly method for the manufacture of superhydrophobic materials with self-cleaning, antifouling, directional transportation, and other characteristics. Herein, an outstanding superhydrophobic material composed of a flexible microconvex aramid paper substrate, micron-scale cone-shaped copper, micro−nanoscale dendritic copper oxide, and hydrophobic copper stearate film has been successfully constructed through delicate architectural design and a convenient preparation approach. Based on the microstructure evolution and composition analysis results, it is revealed that the cone-shaped copper was etched into a dendritic copper oxide structure step by step from the top to bottom and from the outside to inside in an alkaline liquid environment. Moreover, by virtue of the compositional features and structural characteristics, the constructed superhydrophobic material showcased a high contact angle (CA), low sliding angle (SA), high porosity, low surface free energy, and adhesion work. Meanwhile, the dendritic microstructure analysis, the calculation of solid−liquid interfacial tension, and the force analysis of water droplets jointly revealed the mechanism of the bounce and merged bounce of water droplets. Finally, this superhydrophobic material has the functions of self-cleaning, antifouling, and directional transportation, especially by controlling the deformation of the material to realize the transportation of water droplets in a specified direction.

The anisotropic surface prepared by the top-down etching technology shows unique advantages in terms of functional superhydrophobicity. However, it still has a shackle of the smallest etching size, which largely restricts the development of better superhydrophobicity. Therefore, it is still a huge challenge to realize the stepless size adjustment of an anisotropic surface in order to achieve better functionalization. In this work, a bottom-up approach inspired via the modular segmented preparation technology has been used to successfully build an anisotropic, locally ordered functionalized unique superhydrophobic structure, whose contact and rebound time of water droplets is extremely short. Furthermore, this structure with artfully arranged "tracks", which has a relatively large contact angle value, not only lasts more than 15 consecutive bounce cycles in the same direction, where the droplets after merging still bounce, but also exhibits a significant anisotropic sliding behavior, which is presented in different sliding angles, toward droplets rolling in different directions and has lower adhesion work and better self-cleaning and anti-fouling performance. Besides, some mechanisms such as the reduction−replacement−reduction cycle and repulsion−adhesion−switching have been proposed especially in modular preparation and anisotropic sliding behavior. More importantly, this sorted bottom-up structure has great potential for achieving higher efficiency of functionalized superhydrophobicity and other related applications.