Superhydrophobicity and superhydrophilicity of regular nanopatterns.

Centre for Cell Engineering, IBLS, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.
Nano Letters (Impact Factor: 13.03). 11/2005; 5(10):2097-103. DOI: 10.1021/nl051435t
Source: OAI

ABSTRACT The hydrophilicity, hydrophobicity, and sliding behavior of water droplets on nanoasperities of controlled dimensions were investigated experimentally. We show that the "hemi-wicking" theory for hydrophilic SiO(2) samples successfully predicts the experimental advancing angles and that the same patterns, after silanization, become superhydrophobic in agreement with the Cassie-Baxter and Wenzel theories. Our model topographies have the same dimensional scale of some naturally occurring structures that exhibit similar wetting properties. Our results confirm that a forest of hydrophilic/hydrophobic slender pillars is the most effective superwettable/water-repellent configuration. It is shown that the shape and curvature of the edges of the asperities play an important role in determining the advancing angles.

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