An inspiration from purple orchid leaves: Surface characteristics and wettability of nanoscale organometallic coatings electrodeposited on laser-patterned microstructures

Biomimetic superhydrophobic surfaces have attracted considerable attention and are gradually being used in real-life applications. To fabricate such surfaces, a fluorination-based strategy has shown excellent superhydrophobicity and liquid repellency. However, its usage is limited by weak mechanical stability and potential dangers to natural environments and humans. Here, the naturally occurring superhydrophobicity of purple orchid leaves is reported in detail. Inspired by the purple orchid leaves, this study presents an eco-friendly strategy to fabricate biomimetic superhydrophobic surfaces by electrodepositing nanoscale organometallic coatings on laser-patterned microstructures, which aim to enhance the mechanical stability and to approximate biological samples in terms of morphology and composition. Such a biomimetic surface has the same wettability as purple orchid leaves (with a water contact angle of 163.54 ± 1.59°). Experiments indicate that the biomimetic surface has a low roll-off angle (minimum to 4.23 ± 0.39°) and can repel a variety of liquids. The impacting droplets can bounce off the biomimetic surface 6 times within 300 ms, and the stationary droplets can be ejected between two squeezed biomimetic surfaces. These phenomena demonstrate that the biomimetic surface has low adhesion and excellent liquid repellency. Remarkably, the synergistic effect of the nanoscale organometallic coatings and the laser-patterned microstructures greatly enhances the mechanical stability of the biomimetic surfaces, which remains superhydrophobic even after 100 abrasion cycles.