Photothermally promoted recovery of a superhydrophobic surface with anti-icing and de-icing properties for outdoor applications

Ice accumulation is a persistent problem in high-altitude or low-temperature environments, resulting in the abnormal operation of equipment and even fatal accidents. As such, various strategies for removing (de-icing) and preventing (anti-icing) ice from outdoor equipment have been proposed. In this study, a simple photothermal superhydrophobic coating system was developed by combining hydrophilic/hydrophobic silica agglomerates, a polydimethylsiloxane matrix, and organic photothermal dyes (diaminonaphthyl fluorine, DANF) to prevent the loss of superhydrophobicity during ice accumulation. The coating prepared by the spray-coating method exhibited excellent superhydrophobicity with a uniform water contact angle of ∼165° and sliding angle of ∼3.5° over a large area. Sunlight-responsive DANF dye with excellent dispersion stability in common coating resins and higher photothermal conversion efficiency than inorganic photothermal dyes, can increase the surface temperature to ∼30 °C even in an extreme freezing environment (−20 °C) under a near-infrared laser irradiation (808 nm, ∼1 sun). Therefore, under solar irradiation, ice freezing on a superhydrophobic surface can be delayed (anti-icing). Even after ice formation, the initial superhydrophobicity can be recovered through the thermal evaporation of water molecules trapped within the micropillars (de-icing). The proposed photothermal superhydrophobic coatings exhibited uniform photoinduced heating over a large area under sunlight, self-cleaning performance, and adaptability to various substrates, indicating their expected applicability to various types of outdoor equipment for preventing abnormal performance due to ice accumulation.