Abstract
We have prepared superhydrophobic surfaces which become superhydrophilic by heat-treatment at 500°C or irradiation of UV-light. When hydrolyzed fluoroalkyltrimethoxysilane (FAS) was coated on Al2O3 gel film with a roughness of 20 to 50 nm, the films showed superhydrophobicity and high transparency; the contact angle for water of the film was 165° and the transmittance for the visible light was higher than 92%. When the FAS-coated thin films were heat-treated at temperatures higher than 500°C, the films became superhydrophilic; the contact angle for water on the films was smaller than 5°. Thin films of amorphous TiO2 or anatase TiO2 were coated between Al2O3 gel and FAS layer, and the contact angle for water was also about 160°. UV irradiation using high-pressure mercury lamp on these films resulted in the contact angle to be smaller than 5°. When UV light was irradiated through a photomask, superhydrophobic-superhydrophilic micropatterns applicable as a stamper for printing or a substrate of micro-optical components were successfully obtained on the films.
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Tadanaga, K., Morinaga, J. & Minami, T. Formation of Superhydrophobic-Superhydrophilic Pattern on Flowerlike Alumina Thin Film by the Sol-Gel Method. Journal of Sol-Gel Science and Technology 19, 211–214 (2000). https://doi.org/10.1023/A:1008732204421
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DOI: https://doi.org/10.1023/A:1008732204421