Perpetual superhydrophobicity

Giacomello, A, Schimmele, L, Dietrich, S and Tasinkevych, M ORCID: https://orcid.org/0000-0001-6689-1844, 2016. Perpetual superhydrophobicity. Soft Matter, 12 (43), pp. 8927-8934. ISSN 1744-683X

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Abstract

A liquid droplet placed on a geometrically textured surface may take on a “suspended” state, in which the liquid wets only the top of the surface structure, while the remaining geometrical features are occupied by vapor. This superhydrophobic Cassie–Baxter state is characterized by its composite interface which is intrinsically fragile and, if subjected to certain external perturbations, may collapse into the fully wet, so-called Wenzel state. Restoring the superhydrophobic Cassie–Baxter state requires a supply of free energy to the system in order to again nucleate the vapor. Here, we use microscopic classical density functional theory in order to study the Cassie–Baxter to Wenzel and the reverse transition in widely spaced, parallel arrays of rectangular nanogrooves patterned on a hydrophobic flat surface. We demonstrate that if the width of the grooves falls below a threshold value of ca. 7 nm, which depends on the surface chemistry, the Wenzel state becomes thermodynamically unstable even at very large positive pressures, thus realizing a “perpetual” superhydrophobic Cassie–Baxter state by passive means. Building upon this finding, we demonstrate that hierarchical structures can achieve perpetual superhydrophobicity even for micron-sized geometrical textures.

Item Type:	Journal article
Publication Title:	Soft Matter
Creators:	Giacomello, A., Schimmele, L., Dietrich, S. and Tasinkevych, M.
Publisher:	Royal Society of Chemistry (RSC)
Date:	7 October 2016
Volume:	12
Number:	43
ISSN:	1744-683X
Identifiers:	Number Type 10.1039/c6sm01727d DOI 1636210 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Jeremy Silvester
Date Added:	20 Jan 2023 10:45
Last Modified:	20 Jan 2023 10:45
URI:	https://irep.ntu.ac.uk/id/eprint/47994

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