Highly Water-Repellent Nanostructure on Quartz Surface based on Cassie-Baxter Model with Filling Factor

Daisuke Ohori, Sou Takeuchi, Masahiro Sota, Teruhisa Ishida, Yiming Li, Jenn-Hwan Tarng, Kazuhiko Endo, Seiji Samukawa
2020 IEEE Open Journal of Nanotechnology  
We fabricated a highly water-repellent quartz nanopillar (NP) structure to investigate the effect of varying the contact angle (CA) by using 10-nm-order gaps and 10-nm-diameter NPs. Gaps from 15 to 30 nm led to CAs of more than 100°, showing hydrophobicity, to a maximum of 105°. The mechanism of repelling water on quartz could be explained by the Cassie-Baxter model with a filling factor. A gap of more than 30 nm fills with water due to capillarity, but a gap of less than 30 nm causes water to
more » ... nm causes water to be repelled by air. We were able to repeatedly fabricate a quartz NP structure with a controllable gap by using a combination of a bio-template and neutral-beam etching and found this structure to be highly water-repellent. The structure has high durability and optical transparency. As a result, we conclude that it can be used in sensors and lenses on various devices such as cameras and radars. INDEX TERMS Water-repellent nanostructure, quartz nanopillar, bio-template, neutral beam etching.
doi:10.1109/ojnano.2020.2980629 fatcat:yw4sutvv5navlgkfxf3lftetka