Multiscale Effect of Hierarchical Self-Assembled Nanostructures on Superhydrophobic Surface

Abstract

In this work, we describe self-assembled surfaces with a peculiar multiscale organization, from the nanoscale to the microscale, exhibiting the Cassie-Baxter wetting regime with extremely low water adhesion: floating drops regime with roll-off angles < 5°. These surfaces comprise bundles of hierarchical, quasi-one-dimensional (1D) TiO2 nanostructures functionalized with a fluorinated molecule (PFNA). While the hierarchical nanostructures are the result of a gas-phase self-assembly process, their bundles are the result of the capillary forces acting between them when the PFNA solvent evaporates. Nanometric features are found to influence the hydrophobic behavior of the surface, which is enhanced by the micrometric structures up to the achievement of the superhydrophobic Cassie-Baxter state (contact angle (CA) ≫ 150°). Thanks to their high total and diffuse transmittance and their self-cleaning properties, these surfaces could be interesting for several applications such as smart windows and photovoltaics where light management and surface cleanliness play a crucial role. Moreover, the multiscale analysis performed in this work contributes to the understanding of the basic mechanisms behind extreme wetting behaviors.

The fabrication of stable superhydrophobic surfaces using a thin Au/Pd coating over a hydrophilic 3C-SiC nanorod network

“…Superhydrophobicity is generally achieved by creating highly rough fractal surfaces and multiscale hierarchical micro/nano structures and further reducing the surface energy by chemical modifications using hydrophobic coatings [1][2][3][4][5][6][7][8][9]. Generally, fluoropolymers, are used to further modify as-grown micro/nanostructured surfaces to achieve superhydrophobicity.…”

Slippery liquid infused porous surfaces with corrosion resistance potential on aluminum alloy

“…The corrosion current density of the superhydrophobic coatings contacted with 3 M solutions of KCl during 2 h can reached 4.0 Â 10 À11 A cm À2 . Up to now, scholars have done a lot of research on the construction of surface porous microstructure required by SLIPS with various methods including chemical reaction, 24 spraying, 25,26 self-assembly, 27,28 electrochemical coating 29 and laser irradiation. 30 For example, Kim 29 reported a direct fabrication method of SLIPS by electrochemical coating and studied the effect of surface structure size and layer distribution on lubricant retention under high shear conditions by comparing the loss of lubricants, contact angle lag and sliding angle of water and ethanol droplets on different surfaces.…”

On Modulating Interfacial Structure towards Improved Anti-Icing Performance

“…At the same time, the energy and time consumption and the need for periodic treatment make active solutions non-ideal and a "passive approach" through coatings or surface engineering that avoid conventional heating and salting are desired [103,104]. Increasing interest in superhydrophobic [19,21,28,31,34,39,42,43,47,48,53,56,63,65,66,75,[79][80][81][82]84,85,[88][89][90][91][92][105][106][107][108][109][110][111][112][113][114][115][116][117][118], biomimetic [26,37,62,108,117,[119][1...…”