Excellent Dynamic Non-Wetting Performance Induced by Asymmetric Structure at Low Temperatures: Retraction Actuation and Nucleation Inhibition

Abstract

Asymmetric structures have exhibited significant advantages in regulating wetting behavior. Nevertheless, the influence of this unique structural feature on anti-icing performance remains to be further explored. In this work, static/dynamic anti-icing performance is investigated on the asymmetric superhydrophobic structures fabricated by micro-milling combined with electrodeposition. Notably, although the reduction of the degree of asymmetry increases the droplet adhesion force by augmenting the solid-liquid interface, asymmetric structures can still enable the droplet to bounce off the surface through the horizontal Laplace force generated by the contact angle difference between the two sides of the droplet. On this basis, a dynamic behavior criterion for the droplet to detach from the surface is established at low temperatures. Molecular dynamics simulation indicates that the asymmetric structure can reduce the icing probability on the precursor film by inhibiting the nucleation and growth process of water molecules, decreasing the liquid-ice interface, and reducing the adhesion under low temperatures. Generally, specific asymmetric structures with nucleation inhibition characteristics can reduce droplet adhesion and increase the driving force during the droplet retraction stage by enhancing the horizontal Laplace force, effectively improving the dynamic non-wetting performance of the surface at even −40 °C.