Zhang Zhengqing, Kim Hyojeong, Ha Man Yeong, Jang Joonkyung
Department of Nanomaterials Engineering, Pusan National University, Busan 609-735, Republic of Korea.
Phys Chem Chem Phys. 2014 Mar 28;16(12):5613-21. doi: 10.1039/c3cp54976c. Epub 2014 Feb 11.
Using molecular dynamics simulation, we studied the wetting properties of a surface textured with hydrophobic pillars, several nanometers in size. The drying transition of water confined between square or circular pillars was related to the Wenzel (WZ) to Cassie-Baxter (CB) transition of a water droplet deposited on periodic pillars. The inter-pillar spacing at which the drying occurs was compared to that predicted from the continuum theory. Such a comparison revealed that the line tension plays an important role in the drying behavior of the present nm-sized pillars. The water molecules near the pillar walls were layered and ordered in orientation. Our simulation showed a long-lived CB state which eventually turns into the WZ state. In this transition, water slowly penetrated down into the inter-pillar gap until it reached the half height of the pillar, and then quickly reached the base of the pillar.
通过分子动力学模拟，我们研究了表面有尺寸为几纳米的疏水柱结构的润湿性。限制在方形或圆形柱之间的水的干燥转变与沉积在周期性柱上的水滴的文策尔（WZ）到卡西-巴克斯特（CB）转变有关。将发生干燥时的柱间距与连续介质理论预测的间距进行了比较。这样的比较表明，线张力在当前纳米尺寸柱的干燥行为中起着重要作用。靠近柱壁的水分子呈层状排列且取向有序。我们的模拟显示了一种长期存在的CB状态，最终转变为WZ状态。在这个转变过程中，水缓慢向下渗透到柱间间隙，直到到达柱高的一半，然后迅速到达柱底。
