关于光滑固体表面上静止液滴的力学平衡条件的讨论。
Discussion on a mechanical equilibrium condition of a sessile drop on a smooth solid surface.
作者信息
Yonemoto Yukihiro, Kunugi Tomoaki
机构信息
Department of Applied Electronics, Faculty of Industrial Science and Technology, Tokyo University of Science, Yamasaki 2641, Noda, Chiba 278-8510, Japan.
出版信息
J Chem Phys. 2009 Apr 14;130(14):144106. doi: 10.1063/1.3103269.
Young's equation describes an interfacial equilibrium condition of a liquid droplet on a smooth solid surface. This relation is derived by Thomas Young in 1805. It has been discussed until today after his work. In general, Young's equation is discussed from the viewpoint of thermodynamics and derived by minimizing the total free energy of the system with intensive parameters in the total free energy kept constant, i.e., the variation in the total free energy is zero. In the derivation, the virtual work variations in the horizontal and vertical directions of the droplet on the smooth solid are considered independently. However, the virtual work variation at the droplet surface depends on the variation of the horizontal and vertical directions, which are related to an incline of the droplet surface. This point has been overlooked in past studies. In this study, by considering this directional dependency, we derive the modified Young's equation based on the thermodynamics. Finally, we evaluate the modified Young's equation by comparing the analytical solution of the relationship between a contact angle and the contact line radii of the droplet with some experimental data. Moreover, we investigated the line tension itself.
杨氏方程描述了光滑固体表面上液滴的界面平衡条件。该关系式由托马斯·杨于1805年推导得出。自他的研究工作之后，一直被讨论至今。一般来说，杨氏方程是从热力学角度进行讨论的，通过在总自由能中的强度参数保持不变的情况下使系统的总自由能最小化来推导得出，即总自由能的变化为零。在推导过程中，分别考虑了光滑固体上液滴在水平和垂直方向上的虚功变化。然而，液滴表面的虚功变化取决于水平和垂直方向的变化，而这两个方向与液滴表面的倾斜度有关。这一点在过去的研究中被忽视了。在本研究中，通过考虑这种方向依赖性，我们基于热力学推导了修正的杨氏方程。最后，我们通过将液滴接触角与接触线半径之间关系的解析解与一些实验数据进行比较，对修正的杨氏方程进行了评估。此外，我们还研究了线张力本身。
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