Design of surface hierarchy for extreme hydrophobicity
An extreme water-repellent surface is designed and fabricated with a hierarchical integration of nano- and microscale textures. We combined the two readily accessible etching techniques, a standard deep silicon etching, and a gas phase isotropic etching (XeF2) for the uniform formation of double rou...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 25(2009), 11 vom: 02. Juni, Seite 6129-36 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2009
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | An extreme water-repellent surface is designed and fabricated with a hierarchical integration of nano- and microscale textures. We combined the two readily accessible etching techniques, a standard deep silicon etching, and a gas phase isotropic etching (XeF2) for the uniform formation of double roughness on a silicon surface. The fabricated synthetic surface shows the hallmarks of the Lotus effect: durable super water repellency (contact angle>173 degrees) and the sole existence of the Cassie state even with a very large spacing between roughness structures (>1:7.5). We directly demonstrate the absence of the Wenzel's or wetted state through a series of experiments. When a water droplet is squeezed or dropped on the fabricated surface, the contact angle hardly changes and the released droplet instantly springs back without remaining wetted on the surface. We also show that a ball of water droplet keeps bouncing on the surface. Furthermore, the droplet shows very small contact angle hysteresis which can be further used in applications such as super-repellent coating and low-drag microfludics. These properties are attributed to the nano/micro surface texture designed to keep the nonwetting state energetically favorable |
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| Beschreibung: | Date Completed 25.08.2009 Date Revised 26.05.2009 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/la803249t |