Biomimetic fabrication and tunable wetting properties of three-dimensional hierarchical ZnO structures by combining soft lithography templated with lotus leaf and hydrothermal treatments

TL;DR

This paper presents a biomimetic method to fabricate three-dimensional hierarchical ZnO structures with tunable wetting properties, inspired by lotus leaves, using soft lithography and hydrothermal treatments.

Contribution

It introduces a novel combination of soft lithography and hydrothermal growth to create controllable hierarchical ZnO structures with adjustable wettability.

Findings

Hierarchical ZnO structures can be fabricated with controlled morphology.

Wettability can be tuned from superhydrophilic to superhydrophobic.

Surface modification enhances wetting properties.

Abstract

Three-dimensional hierarchical ZnO films with lotus-leaf-like micro/nano structures were successfully fabricated via a biomimetic route combining sol-gel technique, soft lithography and hydrothermal treatments. PDMS mold replicated from a fresh lotus leaf was used to imprint microscale pillar structures directly into a ZnO sol film. Hierarchical ZnO micro/nano structures were subsequently fabricated by a low-temperature hydrothermal growth of secondary ZnO nanorod arrays on the micro-structured ZnO film. The morphology and size of ZnO hierarchical micro/nano structures can be easily controlled by adjusting the hydrothermal reaction time. Wettability of hierarchical ZnO thin films was found to convert from superhydrophilicity to hydrophobicity after a low-surface-energy fluoroalkylsilane modification. Improved wetting properties from hydrophobic to superhydrophobic can be tuned by increasing the growth of ZnO nanorods structures.