A Simple and Widely Applicable Fluorine-Free Robust Superhydrophobic Structure Inspired by Armor in Coatings

The fragility and robustness of superhydrophobic materials have been significant obstacles to their practical applications. While numerous robust superhydrophobic surfaces have been developed, these structures are often complex and costly to prepare and contain fluorine, which has environmental implications. In this study, we constructed a robust fluorine-free superhydrophobic coating by spraying, in which micrometer-sized particles are attached to the substrate surface by a high-viscosity epoxy resin to form a friction-resistant and mechanically damage-resistant shell. The nanoscale structures are then uniformly dispersed in the micrometer-sized rigid shell by spraying, thereby providing the superhydrophobic properties. The experimental results demonstrate that the hydrophobic angle of the superhydrophobic structure is as high as 161.3°. Furthermore, even after 70 cycles of sandpaper abrasion or 70 cycles of tape stripping, the hydrophobic angle remains. The structure can also enhance the corrosion resistance of the coating over an extended period. Furthermore, the low-frequency impedance value is enhanced by a factor of approximately four compared to that of the pure epoxy resin coating. The superhydrophobic structure is not only independent of the type of constructed nanoparticles but also has the potential to be used on a variety of surfaces, which greatly expands the application scenarios of superhydrophobic surfaces. The fact that the structure is independent of the type of nanoparticle used in the construction means that we can use the appropriate nanoparticles to construct superhydrophobic coatings that are more suitable for the current environment.