Yang C, Tartaglino U, Persson B N J
Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425, Jülich, Germany.
Eur Phys J E Soft Matter. 2008 Feb;25(2):139-52. doi: 10.1140/epje/i2007-10271-7. Epub 2008 Mar 3.
We present results of Molecular Dynamics (MD) calculations on the behavior of liquid nanodroplets on rough hydrophobic and hydrophilic solid surfaces. On hydrophobic surfaces, the contact angle for nanodroplets depends strongly on the root-mean-square roughness amplitude, but it is nearly independent of the fractal dimension of the surface. Since increasing the fractal dimension increases the short-wavelength roughness, while the long-wavelength roughness is almost unchanged, we conclude that for hydrophobic interactions the short-wavelength (atomistic) roughness is not very important. We show that the nanodroplet is in a Cassie-like state. For rough hydrophobic surfaces, there is no contact angle hysteresis due to strong thermal fluctuations, which occur at the liquid-solid interface on the nanoscale. On hydrophilic surfaces, however, there is strong contact angle hysteresis due to higher energy barrier. These findings may be very important for the development of artificially biomimetic superhydrophobic surfaces.
我们展示了分子动力学（MD）计算关于液体纳米液滴在粗糙疏水和亲水固体表面行为的结果。在疏水表面上，纳米液滴的接触角强烈依赖于均方根粗糙度幅度，但几乎与表面的分形维数无关。由于增加分形维数会增加短波长粗糙度，而长波长粗糙度几乎不变，我们得出结论，对于疏水相互作用，短波长（原子尺度）粗糙度不是非常重要。我们表明纳米液滴处于类似Cassie的状态。对于粗糙疏水表面，由于在纳米尺度的液 - 固界面处发生的强烈热涨落，不存在接触角滞后现象。然而，在亲水表面上，由于较高的能垒，存在强烈的接触角滞后现象。这些发现对于人工仿生超疏水表面的开发可能非常重要。
