How Micro-/Nanostructure Evolution Influences Dynamic Wetting and Natural Deicing Abilities of Bionic Lotus Surfaces

Anti-icing materials have become increasingly urgent for many fields such as power transmission, aviation, energy, telecommunications, and so on. Bionic lotus hydrophobic surfaces with hierarchical micro-/nanostructures show good potential of delaying ice formation; however, their icephobicity (deicing ability) has been controversial. It is mainly attributed to lack of deep understanding of the correlation between micro-/nanoscale structures, wettability, and icephobicity, as well as effective methods for evaluating the deicing ability close to natural environments. In this article, the natural deicing ability is innovatively proposed on the basis of ice adhesion and the influence of microscale structure evolution on dynamic wetting and deicing ability (both ice adhesion strength and natural deicing time) was systematically investigated. Interestingly, different modes (sticky or slippery) were found in natural deicing of hierarchical hydrophobic surfaces, although their ice adhesion strength was higher than that of smooth surfaces. The mechanism was analyzed from three aspects: mechanics, heat transfer, and dynamic wetting. It is highlighted that the sliding of melted interface is not equal to water droplet sliding (dynamic wetting) before freezing or after deicing but significantly depends on the microscale structure. The fundamental understanding on natural deicing of bionic hydrophobic surfaces will open up a new window for developing new anti-icing materials and technology.