Nonomura Yoshimune, Komura Shigeyuki
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 4-3-16, Jonan, Yonezawa, Yamagata 992-8510, Japan.
J Colloid Interface Sci. 2008 Jan 15;317(2):501-6. doi: 10.1016/j.jcis.2007.09.066. Epub 2007 Sep 29.
The solid particles are adsorbed at liquid-liquid interfaces and form self-assembled structures when the particles have suitable wettability to both liquids. Here, we show theoretically how the extreme roughness on the particle surface affects their adsorption properties. In our previous work, we discussed the adsorption behavior of the solid particles with microstructured surfaces using the so-called Wenzel model [Y. Nonomura et al., J. Phys. Chem. B 110 (2006) 13124]. In the present study, the wettability and the adsorbed position of the particles with extremely rough surfaces are studied based on the Cassie-Baxter model. We predict that the adsorbed position and the interfacial energy depend on the interfacial tensions between the solid and liquid phases, the radius of the particle, and the fraction of the particle surface area that is in contact with the external liquid phase. Interestingly, the initial state of the system governs whether the particle is adsorbed at the interface or not. The shape of the particle is also an important factor which governs the adsorbed position. The disk-shaped particle and the spherical particle which is partially covered with the extremely rough surface, i.e. Janus particle, are adsorbed at the liquid-liquid interface in an oriented state. We should consider not only the interfacial tensions, but also the surface structure and the particle shape to control the adsorption behavior of the particle.
当颗粒对两种液体都具有合适的润湿性时，固体颗粒会吸附在液 - 液界面并形成自组装结构。在此，我们从理论上展示了颗粒表面的极端粗糙度如何影响其吸附特性。在我们之前的工作中，我们使用所谓的文泽尔模型[Y. Nonomura等人，《物理化学杂志B》110 (2006) 13124]讨论了具有微结构表面的固体颗粒的吸附行为。在本研究中，基于卡西 - 巴克斯特模型研究了具有极端粗糙表面的颗粒的润湿性和吸附位置。我们预测，吸附位置和界面能取决于固 - 液相之间的界面张力、颗粒半径以及与外部液相接触的颗粒表面积分数。有趣的是，系统的初始状态决定了颗粒是否会吸附在界面上。颗粒形状也是决定吸附位置的一个重要因素。圆盘状颗粒和部分覆盖有极端粗糙表面的球形颗粒，即 Janus 颗粒，会以定向状态吸附在液 - 液界面上。为了控制颗粒的吸附行为，我们不仅应考虑界面张力，还应考虑表面结构和颗粒形状。
