Page 145 - Handbook of Surface Improvement and Modification

140 Water Repelling (Hydrophobization)

Figure 9.4. Illustration of the fabrication of transparent superhydrophobic coating. f-MWCNTs@PDMS − func-
tionalized multiwalled carbon nanotube/polydimethylsiloxane coating, SNT − silica nanotubes. [Adapted, by
permission, from Zhang, L; Xue, C-H; Cao, M; Zhang, M-M; Li, M; Ma, J-Z, Chem. Eng. J., 320, 244-52, 2017.]

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durability of the building structure. Wind-driven rain is one of the most important mois-
ture sources, therefore, the hydrophobization treatment of the building exterior surface can
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effectively reduce rain absorption and penetration. The bricks from historical buildings
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were treated with water repellents with excellent results.
Transparent coatings with self-cleaning properties were produced for protection of
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outdoor optical devices. Highly transparent, fluorine-free superhydrophobic coatings of
silica nanotubes on glass substrates were fabricated by using polydimethylsiloxane as the
silica source and multiwalled carbon nanotubes as the sacrificial template, followed by
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hydrophobization through chemical vapor deposition of cured PDMS. The optimum coat-
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ing had an average light transmittance higher than 83%, a water contact angle of 165 and
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a slide angle lower than 3 . The superhydrophobic coating had little effect on the power
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generation efficiency of solar cells but outstanding self-cleaning properties. Figure 9.4
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shows the method of fabrication of transparent superhydrophobic coatings.
The superhydrophobic coating on fiberglass cloth was developed for selective
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removal of oil from water. It was fabricated by deposition of amino-silica particles and
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subsequent octadecyltrichlorosilane hydrophobization to have chemical durability. The
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superhydrophobic fiberglass cloth (Figure 9.5) had water contact angle of 154 and sliding