Surface chemistry regulation enables highly durable superhydrophobic coatings with environmental robustness and pH-triggered recoatability

Abstract

Integrating environmental robustness, energy-efficient recoatability and multi-scenario applicability into a single durable coating that can resist the accumulation of liquid, solid, and mold contaminants is critical for the sustainable development of the coatings industry, yet remains a significant challenge. Here, this issue is addressed by developing a novel hydrophilic-hydrophobic conversion strategy to engineer an environmentally robust organic/inorganic hybrid superhydrophobic coating with remarkable anti-soiling properties and pH-induced recoatability. This conversion, achieved through surface chemistry regulation incorporating hydrophobic hydrocarbon chains and aminopropyl functional groups, yields a coating with a high water contact angle (WCA) of 155.4° and a low sliding angle (SA) of 1.3°. Notably, the WCA can reversibly transition to 0° within 15 s under pH adjustment. The wide range of the surface energy variations enables effective recoatability and restores surface wettability in damaged coatings, with an adhesion strength up to 5.34 MPa, allowing for the in-situ reuse of old coatings. The uniform distribution of modified silica nanoparticles within semi-cured epoxy matrix imparts satisfactory environmental durability, allowing the composite coating to retain its superhydrophobicity after enduring various harsh conditions, including 100 cycles of sandpaper abrasion, 70 cycles of tape-peeling, 120 h of water immersion, and 168 h of heat and humidity exposure. Additionally, the coating demonstrates enhanced anti-mold performance, achieving a grade 1 rating. This work introduces a novel design and fabrication method for multifunctional pH-triggered recoatable superhydrophobic coatings with enhanced environmental robustness that significantly extends their lifespan and adaptability.