Fabrication of a superhydrophobic micron-nanoscale hierarchical structured surface for delayed icing and reduced frosting

Abstract

Multifunctional superhydrophobic surfaces with dual-scale hierarchical structures have drawn considerable interest in real-world applications. The complicated fabricating process, higher costs, and poor durability limit the widespread utilization of bio-inspired superhydrophobic surfaces. Herein, we use an effective method to create a micron-nanoscale (dual-scale) hierarchical structure, which is composed of a micron-scaled rough structure constructed by a chemical-etching process and a secondary nanostructure obtained by hydrophobic nano silica (SiO2) modification. The micron-nanoscale hierarchical structured surface has superhydrophobicity with a water contact angle of 161.5°±1.9°. Compared with the micron-scaled rough structure surface, the manufactured micron-nanoscale hierarchical structured surface presented excellent anti-icing properties with a freezing delay time of 5013.6 s at -15 °C. The frost layer on the micron-nanoscale hierarchical structured surface can be rapidly melted to transform into some isolated water droplets in about 7 s due to its ultra-low water adhesion force. Additionally, the prepared superhydrophobic micron-nanoscale hierarchical structured surface has chemical stability and mechanical durability except for the delayed icing and reduced frosting performance. The construction of a micron-nanoscale hierarchical structure is expected to expand superhydrophobic surface applications in anti-icing, anti-frosting, and self-cleaning.