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

摘要

Three-dimensional hierarchical ZnO films with lotus-leaf-like micro/nanostructures were successfully fabricated via a biomimetic route combiningsol-gel technique, soft lithography and hydrothermal treatments. PDMS moldreplicated from a fresh lotus leaf was used to imprint microscale pillarstructures directly into a ZnO sol film. Hierarchical ZnO micro/nano structureswere subsequently fabricated by a low-temperature hydrothermal growth ofsecondary ZnO nanorod arrays on the micro-structured ZnO film. The morphologyand size of ZnO hierarchical micro/nano structures can be easily controlled byadjusting the hydrothermal reaction time. Wettability of hierarchical ZnO thinfilms was found to convert from superhydrophilicity to hydrophobicity after alow-surface-energy fluoroalkylsilane modification. Improved wetting propertiesfrom hydrophobic to superhydrophobic can be tuned by increasing the growth ofZnO nanorods structures.