A viscous switch for liquid-liquid dewetting
A viscous switch for liquid-liquid dewetting
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DOI：
10.1038/s42005-020-0284-8
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发表时间：
2020-01-23
影响因子：
5.5
通讯作者：
McHale, G.
中科院分区：
文献类型：
--
作者：
Edwards, A. M. J.;Ledesma-Aguilar, R.;McHale, G.
液体膜从固体表面的自发脱湿发生在许多重要的过程中，例如印刷和微尺度图案化。经验表明，去湿发生在较高的膜排斥性的表面上更快。在这里，我们展示了如何，出乎意料的是，周围的粘性相可以切换整体去湿速度，使薄膜收缩较慢，增加表面排斥性。我们目前的实验和流体动力学理论，涵盖了五十年的膜和周围的相之间的粘度比。去湿的时间尺度由接近接触线的液-液界面的几何形状和粘度比控制。在小的粘度比，去湿是较慢的低膜排斥性表面上由于在后退膜的边缘处的高耗散。这种情况在高粘度比下相反，由于周围相的消散增加，导致在高膜排斥性表面上的去湿较慢。通常认为，去湿速度随着基底对去湿液体的排斥性而增加，并且在高周围液体粘度下降低。本文从实验和理论上证明了存在一个意想不到的粘度制度，去湿变得更快，不排斥基板。
The spontaneous dewetting of a liquid film from a solid surface occurs in many important processes, such as printing and microscale patterning. Experience suggests that dewetting occurs faster on surfaces of higher film repellency. Here, we show how, unexpectedly, a surrounding viscous phase can switch the overall dewetting speed so that films retract slower with increasing surface repellency. We present experiments and a hydrodynamic theory covering five decades of the viscosity ratio between the film and the surrounding phase. The timescale of dewetting is controlled by the geometry of the liquid-liquid interface close to the contact line and the viscosity ratio. At small viscosity ratio, dewetting is slower on low film-repellency surfaces due to a high dissipation at the edge of the receding film. This situation is reversed at high viscosity ratios, leading to a slower dewetting on high film-repellency surfaces due to the increased dissipation of the advancing surrounding phase.It is generally accepted that the speed of dewetting increases with the repellency of the substrate to the dewetting liquid, and decreases at high surrounding liquid viscosity. This paper demonstrates experimentally and theoretically the existence of an unexpected viscosity regime where dewetting becomes quicker on less repellent substrates.