Govor Leonid V, Parisi Jürgen, Bauer Gottfried H, Reiter Günter
Institute of Physics, University of Oldenburg, D-26111 Oldenburg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 May;71(5 Pt 1):051603. doi: 10.1103/PhysRevE.71.051603. Epub 2005 May 9.
We consider an instability phenomenon in a bilayer structure resulting from phase separation in a thin film of mixed solutions located on a water surface. The top layer consists of a hexane/hexadecylamine solution with thickness d(2) , the lower one of an amyl acetate/cellulose solution with thickness d(1) . During evaporation of the solvents from both layers, their thickness, surface tension, and viscosity change continuously with time. The thickness d(2) decreases significantly faster than the thickness d(1) , because the evaporation rate of hexane is much larger than that of amyl acetate. Eventually, the top layer decomposes into droplets when its thickness d(2) was only a few nm, while the thickness d(1) was still some 100 nm . In addition to the experiments, we present calculations based on energetic arguments which are in good agreement with experimentally determined geometrical parameters of the droplet pattern, such as droplet diameter, droplet height, interdroplet distance, and number of droplets per unit area.
我们考虑一种双层结构中的不稳定性现象，该现象由位于水面上的混合溶液薄膜中的相分离引起。顶层由厚度为d(2)的己烷/十六烷基胺溶液组成，底层由厚度为d(1)的乙酸戊酯/纤维素溶液组成。在两层溶剂蒸发过程中，它们的厚度、表面张力和粘度随时间不断变化。厚度d(2)的减小明显快于厚度d(1)，因为己烷的蒸发速率远大于乙酸戊酯的蒸发速率。最终，当顶层厚度d(2)仅为几纳米时，顶层分解成液滴，而此时厚度d(1)仍约为100纳米。除了实验，我们还基于能量论据进行了计算，这些计算结果与通过实验确定的液滴图案的几何参数，如液滴直径、液滴高度、液滴间距和单位面积内的液滴数量，非常吻合。
