Wetting and dewetting transitions on hierarchical superhydrophobic surfaces |
| |
Authors: | Boreyko Jonathan B Baker Christopher H Poley Celeste R Chen Chuan-Hua |
| |
Affiliation: | Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA. |
| |
Abstract: | Many natural superhydrophobic structures have hierarchical two-tier roughness which is empirically known to promote robust superhydrophobicity. We report the wetting and dewetting properties of two-tier roughness as a function of the wettability of the working fluid, where the surface tension of water/ethanol drops is tuned by the mixing ratio, and compare the results to one-tier roughness. When the ethanol concentration of deposited drops is gradually increased on one-tier control samples, the impalement of the microtier-only surface occurs at a lower ethanol concentration compared to the nanotier-only surface. The corresponding two-tier surface exhibits a two-stage wetting transition, first for the impalement of the microscale texture and then for the nanoscale one. The impaled drops are subsequently subjected to vibration-induced dewetting. Drops impaling one-tier surfaces could not be dewetted; neither could drops impaling both tiers of the two-tier roughness. However, on the two-tier surface, drops impaling only the microscale roughness exhibited a full dewetting transition upon vibration. Our work suggests that two-tier roughness is essential for preventing catastrophic, irreversible wetting of superhydrophobic surfaces. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|