Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697, USA.
Langmuir. 2010 Oct 5;26(19):15316-24. doi: 10.1021/la102268n.
The equilibrium configuration of a nonwetted three fluid system takes the form of a floating liquid lens, where the lens resides between an upper and lower phase. The axisymmetric profiles of the three interfaces can be computed by solving the nonlinear Young-Laplace differential equation for each interface with coupled boundary conditions at the contact line. Here we describe a numerical method applicable to sessile or pendant lenses and provide a free, downloadable Mathematica Player file which uses a graphical interface for analyzing and plotting lens profiles. The results of the calculations were compared to optical photographs of various liquid lens systems which were analyzed using basic ray-tracing and Moiré imaging. The lens profile calculator, together with a measurement of the lens radius for a known volume, provides a simple and convenient method of determining the spreading coefficient (S) of a liquid lens system if all other fluid parameters are known. If surfactants are present, the subphase surface tension must also be self-consistently determined. A procedure is described for extracting characteristic features in the optical images to uniquely determine both parameters. The method gave good agreement with literature values for pure fluids such as alkanes on water and also for systems with a surfactant (hexadecane/DTAB), which show a transition from partial wetting to the pseudopartial wetting regime. Our technique is the analog of axisymmetric drop shape analysis, applied to a three fluid system.
非润湿三相体系的平衡构型呈浮液透镜状，透镜位于上、下相之间。通过求解每个界面的非线性 Young-Laplace 微分方程，并在接触线处施加耦合边界条件，可以计算出三个界面的轴对称轮廓。在这里，我们描述了一种适用于固着或悬滴透镜的数值方法，并提供了一个免费的 Mathematica 播放器文件，该文件使用图形界面来分析和绘制透镜轮廓。计算结果与各种液体透镜系统的光学照片进行了比较，这些照片是通过基本光线追踪和云纹成像进行分析的。透镜轮廓计算器结合已知体积的透镜半径测量值，如果其他所有流体参数都已知，则为确定液体透镜系统的扩展系数 (S) 提供了一种简单方便的方法。如果存在表面活性剂，则亚相表面张力也必须自洽确定。本文描述了一种从光学图像中提取特征的方法，该方法可以唯一确定两个参数。该方法与纯流体（例如在水上的烷烃）以及具有表面活性剂（十六烷/ DTAB）的体系的文献值吻合良好，后者表现出从部分润湿到伪部分润湿的转变。我们的技术是轴对称液滴形状分析的模拟，适用于三相体系。
