Wettability of dragonfly wings: the structure detection and theoretical modeling

Hydrophobic surfaces have gained extensive attention in recent decades for their potential applications. The hydrophobic properties of dragonfly's (Pantala flavescens) wings were measured, and the water contact angles (WCAs) of the distal and basal part of a dragonfly's wing were 134.9 degrees and 125.8 degrees, respectively. Images obtained by optical microscopy and scanning electron microscopy showed the microstructures and nanostructures on the wing surface. Microstructures appeared as cell block patterns, and the size of the blocks decreased from the basal to distal part. However, no significant differences of chemical composition between the two parts were detected by X-ray photoelectron spectroscopy. To understand the correlation between the structures and WCA, a double roughness structure model was built theoretically with simplified lattice patterns, and the theoretical model was well fitted with empirical wettability of the dragonfly's wing. Copyright (C) 2012 John Wiley & Sons, Ltd.