Construction of a robust MOF-based superhydrophobic composite coating with the excellent performance in antifouling, drag reduction, and organic photodegradation

The superhydrophobic coating blocks a certain air layer between the solid surface and the liquid, thereby changing the interaction between the surface and water, and has potential applications in enhancing buoyancy and drag reduction. Consequently, a superhydrophobic coating designed to reduce drag (the contact angle was up to 168°) was prepared in this study. The coating was applied to copper mesh by spraying a mixed solution comprising ZIF-8 particles, waterborne polyurethane, and a silane coupling agent, resulting in a significant enhancement of load capacity. The superhydrophobic coating can change the contact mode between the copper mesh and water, leading to a remarkable sevenfold increase in the maximum load capacity when compared with the uncoated sample, primarily due to its' increased buoyancy. In addition, the self-made superhydrophobic model ship exhibited an impressive drag reduction efficiency of up to 36 %, indicating that it has significant drag reduction capability. It's worth noting that once water enters, the superhydrophobic spheres will form a gas cavity, which is critical for the coating's drag reduction capability. The self-cleaning property of this superhydrophobic composite coating is highly promising. Moreover, it can also purify seawater by utilizing ZIF-8's photocatalytic activity to degrade organic contaminant. Therefore, in the context of actual ships and underwater vehicles, this superhydrophobic coating holds potential as a relevant strategy for enhancing buoyancy and reducing drag, thus offering commercial value.