Construction of a Double Covalent-Network Structured Superhydrophobic Composite Coating with Mechanochemical Robustness and Self-Cleaning Property

Superhydrophobic surfaces with self-cleaning capability have attracted extensive attention; however, their practical application is severely hindered by poor mechanochemical robustness, limited scalability of fabrication methods, and high cost. Herein, a durable superhydrophobic composite coating reinforced by a double covalent-network architecture and an epoxy bonding layer is reported. In this design, covalent networks act as molecular bridges and rigid skeletons among nanoparticles, while epoxy resin enhances the interfacial adhesion. The coating can be constructed stepwise on various substrates via a facile spray-coating process. The resulting coating exhibits a high water contact angle exceeding 162° and a low roll-off angle of approximately 6°. Durability tests indicate that the coatings maintained excellent water-repellency after exposure to various treatments, including heating to 300 °C, immersion in acidic or alkaline solutions for several hours, and sustained abrasion (over 5600 cm) under a pressure of 541 Pa, which demonstrated robust mechanochemical stability. Owing to its ultralow water adhesion, the coating also shows an excellent self-cleaning performance. Benefiting from its superior durability, chemical stability, and scalable fabrication, this coating shows strong potential for practical applications including infrastructure anticorrosion, building waterproofing, and marine antifouling.