Bommer Stefan, Cartellier Florian, Jachalski Sebastian, Peschka Dirk, Seemann Ralf, Wagner Barbara
Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany.
Eur Phys J E Soft Matter. 2013 Aug;36(8):87. doi: 10.1140/epje/i2013-13087-x. Epub 2013 Aug 14.
The morphological path of droplets on a liquid substrate towards equilibrium is investigated experimentally and theoretically. The droplets emerge in the late stage of a dewetting process of short chained polystyrene (PS) dewetting from liquid polymethyl-methacrylate (PMMA). The three-dimensional droplet profiles are obtained experimentally by combining the in situ imaged PS/air interface during equilibration and the ex situ imaged PS/PMMA interface after removal of the PS by a selective solvent. Numerically the transient drop shapes are calculated by solving the thin-film equation in lubrication approximation using the experimentally determined input parameter like viscosity, film thickness and surface tensions. The numerically obtained droplet morphologies and time scales agree very well with the experimental drop shapes. An unexpected observation is that droplets with identical volumes synchronise their motion and become independent of the initial geometry long time before equilibrium is reached.
通过实验和理论研究了液体基底上液滴达到平衡的形态学路径。这些液滴出现在短链聚苯乙烯（PS）从液态聚甲基丙烯酸甲酯（PMMA）脱湿过程的后期。通过结合平衡过程中原位成像的PS/空气界面以及用选择性溶剂去除PS后异位成像的PS/PMMA界面，实验获得了三维液滴轮廓。在数值上，利用实验确定的输入参数（如粘度、膜厚和表面张力），通过在润滑近似下求解薄膜方程来计算瞬态液滴形状。数值获得的液滴形态和时间尺度与实验液滴形状非常吻合。一个意外的观察结果是，具有相同体积的液滴在达到平衡之前很长时间就会同步它们的运动，并且变得与初始几何形状无关。
