Gradient wettability induced by deterministically patterned nanostructures

Siyi Min; Shijie Li; Zhouyang Zhu; Wei Li; Xin Tang; Chuwei Liang; Liqiu Wang; Xing Cheng; Wen-Di Li

doi:10.1038/s41378-020-00215-0

Gradient wettability induced by deterministically patterned nanostructures

Microsyst Nanoeng. 2020 Nov 30:6:106. doi: 10.1038/s41378-020-00215-0. eCollection 2020.

Authors

Siyi Min^{1

2}, Shijie Li¹, Zhouyang Zhu¹, Wei Li¹, Xin Tang¹, Chuwei Liang¹, Liqiu Wang^{1

3}, Xing Cheng², Wen-Di Li^{1

3}

Affiliations

¹ Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077 China.
² Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518052 China.
³ HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, 311305 Zhejiang China.

Abstract

We report a large-scale surface with continuously varying wettability induced by ordered gradient nanostructures. The gradient pattern is generated from nonuniform interference lithography by utilizing the Gaussian-shaped intensity distribution of two coherent laser beams. We also develop a facile fabrication method to directly transfer a photoresist pattern into an ultraviolet (UV)-cured high-strength replication molding material, which eliminates the need for high-cost reactive ion etching and e-beam evaporation during the mold fabrication process. This facile mold is then used for the reproducible production of surfaces with gradient wettability using thermal-nanoimprint lithography (NIL). In addition, the wetting behavior of water droplets on the surface with the gradient nanostructures and therefore gradient wettability is investigated. A hybrid wetting model is proposed and theoretically captures the contact angle measurement results, shedding light on the wetting behavior of a liquid on structures patterned at the nanoscale.

Keywords: Structural properties.