Robust photothermal superhydrophobic coating based on fluorinated epoxy resin and SiO2/carbon black with highly efficient anti-icing performance

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Abstract
Superhydrophobic photothermal anti-icing coatings represent a crucial strategy for addressing outdoor icing challenges. However, they still face significant challenges regarding long-term durability and large-scale production. In this study, a facile and cost-effective one-step spraying strategy is proposed to construct a robust photothermal superhydrophobic composite coating based on a modified epoxy resin system. By introducing an epoxy oligomer grafted with perfluorodecyltrimethoxysilane and precisely regulating the synergistic ratio of 14 nm nanoscale silicon dioxide (SiO2) and carbon black, a dual-scale hierarchical superhydrophobic structure was successfully fabricated. The SiO2 nanoparticles act as physical spacers to effectively suppress carbon black agglomeration, which not only induces a light-trapping effect with an optical absorptance exceeding 96% to enhance solar energy harvesting, but also endows the coating with excellent superhydrophobicity (water contact angle of 169.2°, sliding angle of 1.7°). Owing to the overall homogeneity and structural self-similarity of the composite coating, it exhibits exceptional mechanical robustness and weatherability, maintaining its anti-icing and liquid-repellent functions even after 180 tape peeling cycles, 45 sandpaper abrasion cycles, and 288 hours of intense UV aging. Notably, the coating demonstrates superior thermal stability, retaining excellent superhydrophobic characteristics after continuous annealing in a muffle furnace at 200 °C for 7 days, thereby effectively overcoming the industrial bottleneck of performance degradation in photothermal coatings under severe summer sun exposure. In extreme anti-icing tests at -30 °C, The coating significantly reduced the adhesion strength of ice on the aluminum substrate from 80.4 kPa to 21.5 kPa; concurrently, the complete freezing time of water droplets was extended from 27 s on aluminum to 93 s. Under xenon lamp irradiation at 25 mW/cm2, its freezing delay time was prolonged from 46 s on aluminum to 214 s. Under an irradiation intensity of 50 mW/cm2, the coating relies on an efficient interfacial melting mechanism to shed a large 1.5 cm3 ice block in merely 73.3 s. This research provides a novel perspective for the fabrication of low-cost, long-lifespan coatings with active-passive synergistic anti-icing performance for harsh extreme environments.

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