Biphilic surfaces having spatially distinct wetting have the potential to enable a plethora of applications ranging from fog harvesting, microfluidics, advanced manufacturing, and pumpless fluid transfer. However, complex and costly fabrication along with poor durability have hindered the widespread utilization of biphilic surfaces. Here, hierarchical biphilic micro/nanostructured surfaces passively functionalized by the atmosphere are demonstrated as a platform to create scalable and abrasion‐resistant biphilic interfaces. Biphilic hierarchical copper oxide (CuO) nanowires are fabricated on copper substrates via laser ablation followed by thermal oxidation. The surfaces spontaneously become globally superhydrophobic and locally hydrophilic due to the adsorption of airborne volatile organic compounds on the ultrahigh surface energy CuO nanowires. The curvature‐dependent spatial variation in nanowire morphology enables local roughness variation and wetting contrast without the need for selective functionalization. Coalescence‐induced droplet jumping and water vapor condensation experiments demonstrate global superhydrophobicity with discrete local hydrophilicity. In addition to enhanced fog harvesting rates, the surfaces are demonstrated to have repeatable self‐healing function with enhanced abrasion resistance compared to single‐tier structured surfaces. The work not only develops a facile method of fabricating scalable biphilic surfaces via nanoscale structure variation and atmosphere‐mediated surface modification, but also provides insights into the role of wetting contrast on droplet dynamics.
Wetting phenomena and superhydrophobic surfaces are ubiquitous in nature and have recently been explored widely in scientific and engineering applications. The understanding and control of surface superhydrophobicity are not only fundamentally intriguing but also practically important to provide unique and regulated functionalities to natural species and industrial applications. Here, the fundamentals of wetting phenomena are critically reviewed that especially apply to superhydrophobicity, putting an emphasis on the clarification of contact angles, the quantification of droplet retention force, and the role of contact line. The fundamentals of how the droplet retention is determined by the surface features are discussed and advanced analytical models for the prediction of contact angles and retentive forces are introduced. Applications are further discussed whose functionalities largely depend on the droplet retention, including directional droplet transport, anti‐icing, and water harvesting.
more » « less- NSF-PAR ID:
- 10454715
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 8
- Issue:
- 2
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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