纳米沟槽表面润湿特性的分子动力学模拟

Molecular Dynamics Simulations on Wettability of Nano-grooved Surface

理解表面润湿现象及其影响因素,并进而控制表面润湿性,在能源工程领域中具有重要意义。本文采用分子动力学模拟得到了二维液滴与纳米沟槽结构表面的接触状态,考察了不同液固相互作用强度下,沟槽深度和沟槽宽度等参数对液滴在表面的接触角和润湿模式的影响。模拟结果表明:沟槽结构的引入使得表面疏水性相对光滑表面增强;沟槽深度增加,接触角增大,但当沟槽深度大于一定值后,接触角不再随沟槽深度发生显著变化;沟槽宽度增加,接触角总体增大;一定条件下,沟槽深度和宽度的改变可导致润湿模式的转变。此外,将模拟结果与经典模型对比,发现接触角的变化规律与Cassie-Baxter理论符合较好,与Wenzel理论偏差较大。

Understanding the wettability phenomenon and its influence factors, thus further modifying the surface wettability, are important issue in the energy engineering field. By the means of molecular dynamics simulations, the static contact angles of two-dimensional water droplet on the nano-grooved surfaces were obtained. The effects of the groove depth and hollow width on the contact angle and wetting regime under different intensities of interactions between water and surface molecules were analyzed. The results show that the nano-grooves make the surface more hydrophobic; when the groove depth exceeds a certain value, the contact angle remains insensitive to the groove depth; while increasing the hollow width, the contact angle shows a growing tendency; the changes of the groove depth and hollow width may also result in the transition of the wetting regime; moreover, the variation of the contact angle is in agreement with Cassie-Baxter equation, but does not match with the Wenzel theory.