Waterborne, non-fluorinated and durable anti-icing superhydrophobic coatings based on diatomaceous earth

Superhydrophobic coatings have great potential for anti-icing compared with conventional techniques (e.g., thermal melting, chemical release and mechanical vibration), but suffer from short water freezing time, environment-unfriendliness, low stability, etc. Here, we report the preparation of waterborne, non-fluorinated and durable anti-icing superhydrophobic coatings based on diatomaceous earth (DE). The coatings are prepared by sequentially spray-coating a waterborne polyurethane aqueous solution and a hexadecyl polysiloxane modified DE aqueous suspension onto various substrates with waterborne polyurethane as the adhesive layer. The coatings have excellent superhydrophobicity (contact angle = 168.1 ± 1.6°, sliding angle = 4.9 ± 0.7°). Moreover, the coatings show excellent mechanical, chemical and environmental stability. Furthermore, the coatings on the Mg alloy plate significantly increase the water freezing time to 361 s and reduce the ice adhesion strength to 73.9 kPa at −15 °C due to the air cushion trapped in the micro-/nanostructure with low surface energy. The air cushion prevents heat transfer from the substrates to water in the icing process, minimizes the mechanical anchoring effect of ice on the coating, and generates a loose ice structure. The coatings are very promising for practical anti-icing due to the excellent anti-icing performance, high stability and the environmentally friendly preparation method.