Re-Entrant Super-Repellent Metallic Structures for Robust Anti-Icing.

Superhydrophobic surfaces exhibit significant potential for anti-icing applications. However, sustaining the superhydrophobic Cassie-Baxter state under conditions of low temperature, high humidity, and dynamic impacts remains a critical challenge. Re-entrant structures, as a milestone advance in the study of super-repellent surfaces, not only render material surfaces the Cassie-Baxter state when contacting with liquids beyond water, but also raise a capability in keeping the super-repellent surfaces effective under broader environmental conditions. However, most studies on re-entrant super-repellent structures focus on their room-temperature performances. The water-repellent capabilities of re-entrant structures under low-temperature conditions and their anti-icing performances, in particular, are yet to be elucidated. Herein, re-entrant structures are designed and fabricated directly on metal surfaces, which exhibit remarkable anti-icing performances, including ultra-long icing delay (> 600 min), ultra-low ice adhesion strength (1.6 kPa), and significant durability (ice adhesion strength staying < 25 kPa after 100 deicing cycles). Through systematic characterizations and careful thermodynamic analysis, the underlying mechanisms for the remarkable anti-icing performances are revealed. This study not only validates the effectiveness of re-entrant structures under low-temperature conditions but also engineers the design and fabrication of re-entrant structures for excellent anti-icing performances, establishing a new paradigm for designing robust anti-icing surfaces.