Bionic design of multi-scale superhydrophobic textures to smash impacted droplets: An anti-icing strategy

The ice formed on aircraft as a result of the freezing of supercooled large droplets (SLD) presents a significant safety risk to flight safety. Mitigating or inhibiting SLD icing has attracted considerable attention from researchers. Although superhydrophobic surfaces have demonstrated potential in reducing contact time to achieve anti-icing, their effectiveness has been limited by the issue of droplets eventually staying and freezing on the horizontal surface after bouncing. To address this limitation, droplets breaking up and flying away from the surface is an effective method of preventing them from adhering to the surface, thereby enhancing the anti-icing performance of superhydrophobic surfaces. This study observed that droplets of high Weber numbers impacting barnyard grass break up into smaller droplets through liquid column disintegration and quickly fly away from the leaf. This behavior is attributed to the anisotropic spreading and retraction of the liquid film caused by the surface structure, resulting in the formation of a scattering liquid column that is more unstable than that of a droplet of the same volume. Additionally, SLD impacting a bionic surface inspired by barnyard grass also break up and fly away, leaving no ice on the bionic superhydrophobic surface, whereas those impacting a smooth superhydrophobic surface retract into spherical droplets that eventually freeze on the surface. This research contributes to the advancement of SLD anti-icing studies and provides a strategy and bionic structure to enhance anti-icing performance further.