Air pocket-optimization strategy for micro/nanostructures fabricated by femtosecond laser technology for anti-icing performance improvement

The primary method for improving the anti-icing performance of metals involves enhancing their surface superhydrophobic properties. However, the superhydrophobic properties of micro/nanostructured surfaces often deteriorate in low-temperature environments, limiting their performance in anti-icing applications. Herein, instead of the traditional optimization of surface superhydrophobic properties, microscale structure morphology was designed and fabricated by optimizing air pocket types and parameters to address the hydrophobicity degradation at low temperatures effectively. Anti-icing tests revealed that the anti-icing performance of an optimized surface can be further improved in three critical stages over the entire anti-icing process compared to structural surfaces with similar high surface hydrophobicity and low apparent solid-liquid contact area: at the droplet impact stage, the droplet rebounds successfully from the surface, exhibiting excellent dynamic hydrophobicity even at -15 C. At the droplet contact stage, the freezing time of the static droplet can be extended by -1.5 times, which is more pronounced at low temperatures. At the droplet freezing stage, the ice adhesion strength of the surface decreases by -3.5 times, attributable to the enhanced Cassie state stability induced by air pocket optimizations during the anti-icing process. This optimization maintains a small actual contact area and prevents water droplets from infiltrating the surface. Furthermore, the ice adhesion strength is reduced by the increased ice-interface defects. Exploring the flexible design capabilities and industrial applicability of femtosecond laser technology for fabricating micro/nanostructures, the proposed structural optimization addresses the deterioration in the anti-icing performance in low-temperature environments and offers fresh insights for the development and application of superhydrophobic anti-icing functional surfaces.