Kusumaatmaja H, Yeomans J M
The Rudolf Peierls Centre for Theoretical Physics, Oxford University, 1 Keble Road, Oxford OX1 3NP, United Kingdom.
Langmuir. 2007 May 22;23(11):6019-32. doi: 10.1021/la063218t. Epub 2007 Apr 24.
We investigate contact angle hysteresis on chemically patterned and superhydrophobic surfaces, as the drop volume is quasistatically increased and decreased. We consider both two (cylindrical drops) and three (spherical drops) dimensions using analytical and numerical approaches to minimize the free energy of the drop. In two dimensions, we find, in agreement with other authors, a slip, jump, stick motion of the contact line. In three dimensions, this behavior persists, but the position and magnitude of the contact line jumps are sensitive to the details of the surface patterning. In two dimensions, we identify analytically the advancing and receding contact angles on the different surfaces, and we use numerical insights to argue that these provide bounds for the three-dimensional cases. We present explicit simulations to show that a simple average over the disorder is not sufficient to predict the details of the contact angle hysteresis and to support an explanation for the low contact angle hysteresis of suspended drops on superhydrophobic surfaces.
我们研究了在化学图案化和超疏水表面上，随着液滴体积准静态增加和减少时的接触角滞后现象。我们使用解析和数值方法来最小化液滴的自由能，考虑了二维（圆柱形液滴）和三维（球形液滴）两种情况。在二维情况下，我们与其他作者的研究结果一致，发现接触线存在滑动、跳跃、粘着运动。在三维情况下，这种行为仍然存在，但接触线跳跃的位置和大小对表面图案的细节很敏感。在二维情况下，我们通过解析确定了不同表面上的前进接触角和后退接触角，并利用数值分析认为这些为三维情况提供了边界。我们给出了明确的模拟结果，表明对无序情况进行简单平均不足以预测接触角滞后的细节，并支持对超疏水表面上悬浮液滴低接触角滞后现象的一种解释。
