Bertrand E, Blake T D, Ledauphin V, Ogonowski G, Coninck J De, Fornasiero D, Ralston J
Centre for Research in Molecular Modelling, University of Mons-Hainaut, Parc Initialis, Av. Copernic 1, 7000 Mons, Belgium.
Langmuir. 2007 Mar 27;23(7):3774-85. doi: 10.1021/la062920m. Epub 2007 Mar 1.
Large-scale molecular dynamics simulations are used to model the dewetting of solid surfaces by partially wetting thin liquid films. Two levels of solid-liquid interaction are considered that give rise to large equilibrium contact angles. The initial length and thickness of the films are varied over a wide range at the nanoscale. Spontaneous dewetting is initiated by removing a band of molecules either from each end of the film or from its center. As observed experimentally and in previous simulations, the films recede at an initially constant speed, creating a growing rim of liquid with a constant receding dynamic contact angle. Consistent with the current understanding of wetting dynamics, film recession is faster on the more poorly wetted surface to an extent that cannot be explained solely by the increase in the surface tension driving force. In addition, the rates of recession of the thinnest films are found to increase with decreasing film thickness. These new results imply not only that the mobility of the liquid molecules adjacent to the solid increases with decreasing solid-liquid interactions, but also that the mobility adjacent to the free surface of the film is higher than in the bulk, so that the effective viscosity of the film decreases with thickness.
大规模分子动力学模拟用于对部分润湿的薄液膜使固体表面去湿的过程进行建模。考虑了两种导致大平衡接触角的固液相互作用水平。在纳米尺度上，膜的初始长度和厚度在很宽的范围内变化。通过从膜的两端或中心去除一条分子带来引发自发去湿。正如实验观察和先前模拟中所发现的，膜以初始恒定速度后退，形成一个动态接触角恒定的不断增长的液环。与当前对润湿动力学的理解一致，在润湿性较差的表面上膜后退得更快，其程度无法仅由表面张力驱动力的增加来解释。此外，发现最薄液膜的后退速率随膜厚度减小而增加。这些新结果不仅意味着与固体相邻的液体分子的迁移率随固液相互作用的减小而增加，而且还意味着与膜的自由表面相邻处的迁移率高于本体中的迁移率，从而膜的有效粘度随厚度减小。
