Totally Waterborne, Nonfluorinated, Mechanically Robust, and Self-Healing Superhydrophobic Coatings for Actual Anti-Icing

Bioinspired superhydrophobic coatings are of great interest in academic and industrial areas. However, their real-world applications are hindered by some main bottlenecks, especially the pollutive preparation methods (e.g., organic solvents and fluorinated compounds) and poor mechanical stability. Here, we report for the first time the totally waterborne, nonfluorinated, mechanically robust, and self-healing superhydrophobic coatings. The coatings were fabricated by spray-coating polyurethane (PU) aqueous solution and a hexadecyl polysiloxane-modified SiO2 (SiO2@HD-POS) aqueous suspension onto substrates using PU as the adhesive. The SiO2@HD-POS suspension was synthesized by HCl-catalyzed reactions among hexadecyltrimethoxysilane, tetraethoxysilane, and SiO2 nanoparticles. Besides high superhydrophobicity, the coatings exhibit exceptional mechanical stability against sandpaper abrasion for 200 cycles at 9.8 kPa and tape-peeling for 200 cycles at 90.5 kPa because of high durability and unique hierarchical macro-/nanostructure of the coating as well as solid lubrication of the SiO2@HD-POS nanoparticles fallen off from the coatings. The coatings also show fast and stable self-healing capability owing to migration of the healing agent (HD-POS) to the damaged surface. Moreover, the coatings exhibit good static and dynamic anti-icing performance in outdoor environment (−15 °C, relative humidity = 54%). The superhydrophobic coatings may be used in various areas because the main bottlenecks have been successfully broken.