title: Superhydrophobicity of natural and artificial surfaces under controlled condensation conditions.
abstract: In this paper, we have comparatively investigated the stability of superhydrophobic behaviors of fresh and biomimetic lotus leaf surfaces under controlled water condensation conditions. The binary micro/nano structures of the superhydrophobic surfaces are observed with electron micrographs. Contact and sliding angles are evaluated by syringing water droplets on the substrates with surface temperatures and humidity precisely controlled between -10 and 30 °C, and RH = 10, 30, 60, and 90%. According to the calculations on the solid-liquid contact area fraction in different environmental conditions based on a micro/nano binary structure model, the effects of condensed water on superhydrophobic surfaces are assessed quantitatively. Both the calculated and experimental results indicate that the temperature difference between surface temperature and the dew point during measurement is essential to the occurrence of water condensation while the effect of condensation on the surface wettability also depends on the topology of hierarchical structured surfaces. The loss of water repellency that usually appears on the artificial superhydrophobic surface under low temperature and high humidity conditions is proved to be reversible, showing a bidirectional transition of the equilibrium state between Wenzel and Cassie-Baxter.
authors: Polymer Science and Engineering Department, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, Jiangsu 210093, China.
authors: Long
authors: L
authors: Yin
authors: Lin
authors: L
authors: Zhu
authors: Qingjun
authors: Q
authors: Wang
authors: Jianfu
authors: J
authors: Ding
authors: Qingmin
authors: Q
authors: Chen
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D055032:Electron Microscope Tomography; D006813:Humidity; D057927:Hydrophobic and Hydrophilic Interactions; D000070116:Lotus / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature