How micropatterns affect the anti-icing performance of superhydrophobic surfaces

Abstract

• Four dynamic-freezing modes are identified on superhydrophobic surfaces (SHSs). • The capillary evacuation contributes to an excellent anti-icing performance. • The coupling effects of nucleation and wetting dynamics are analyzed in detail. • A dimensionless number is put forward to optimally design anti-icing SHSs. Superhydrophobic surfaces (SHSs) have shown significant potential in the anti-icing field over the past decade. In this work, we conduct impact experiments of supercooled drops on SHSs with various micropillar arrays and show how micropatterns contribute to efficient anti-icing performances. Here, we found four dynamic-freezing modes: partial penetration, penetration with evacuation, penetration without evacuation, and internal rupture, and obtained the phase diagrams of these modes in terms of the structural parameters. The hierarchical SHSs, where penetration with evacuation and internal rupture can occur, present more excellent anti-icing performances than single-tier SHSs. The capillary evacuation is proved to play an important role in the reduction of contact time and contact area. A quantitative interpretation of the influence of the capillary evacuation on the contact time is obtained, which demonstrates the potential anti-icing ability of hierarchical SHSs. Coupling the effect of nucleation and wetting dynamics on hierarchical SHSs with capillary evacuation, we put forward a dimensionless number, combined the structural parameters and Weber number We , which is important for optimally designed anti-icing micropatterns of SHSs.