Department of Polymer Engineering, Amirkabir University of Technology, 424 Hafez Avenue, Tehran, Iran.
J Colloid Interface Sci. 2010 Apr 15;344(2):575-83. doi: 10.1016/j.jcis.2009.12.058. Epub 2010 Jan 11.
Nature-made superhydrophobic surfaces, such as lotus leaves, have a dual scale roughness (in micro and nanoscales) which is the main reason for their unique wettability. While there are a lot of experimental studies on wettability of hierarchical roughness, there is a lack of a thorough analysis of the contribution of micro and nanoscale roughness on wettability behavior despite interesting features these surfaces have. In this paper, a thermodynamic approach has been used to predict the wetting behavior of water droplet on a dual scale roughness. The predictions made by the model are compared with experimental results reported in the literature. The thermodynamic analysis has also been used to provide an insight into the origin of the special hydrophobicity of surfaces with dual scale roughness. It was found that there is an interaction between micro and nanoscale roughness on wettability of each other which results in a synergy among the components of roughness in enhancing hydrophobicity. All possible wetting states of a surface with dual scale roughness were presented in a wetting map. The contact angle for each state was also calculated to determine the maximum water repellency condition.
天然超疏水表面，如荷叶，具有双重尺度的粗糙度（在微观和纳米尺度上），这是其独特润湿性的主要原因。虽然有很多关于分级粗糙度润湿性的实验研究，但缺乏对微纳尺度粗糙度对润湿性行为的贡献的深入分析，尽管这些表面具有有趣的特征。在本文中，采用热力学方法预测了液滴在双重粗糙度上的润湿行为。模型的预测结果与文献中报道的实验结果进行了比较。热力学分析还用于深入了解具有双重粗糙度表面特殊疏水性的起源。结果发现，微纳尺度粗糙度之间存在相互作用，这导致粗糙度各组成部分在增强疏水性方面产生协同作用。在润湿图中呈现了具有双重粗糙度表面的所有可能润湿状态。还计算了每个状态的接触角，以确定最大的拒水条件。
