Dynamics of evaporative colloidal patterning
Dynamics of evaporative colloidal patterning
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DOI：
10.1063/1.4930283
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发表时间：
2015-09-01
影响因子：
4.6
通讯作者：
Mahadevan, L.
中科院分区：
文献类型：
--
作者：
Kaplan, C. Nadir;Wu, Ning;Mahadevan, L.
干燥的悬浮液通常会留下复杂的微粒图案，就像桌子上的咖啡渍一样。在这里，我们考虑周期性带状或均匀固体膜形成的动力学垂直板部分悬浮在干燥的胶体溶液。直接观察使我们能够可视化带和膜沉积的动力学，其中两者都是由多层紧密堆积的粒子组成的。我们进一步看到，当胶体浓度变化时，在带状和成膜之间存在过渡。液体半月板沿板块运动的最小理论揭示了带状及其向膜状过渡的动力学，这是沉积和蒸发速率比的函数。我们还提供了溶解在液体中的胶体的互补多相模型，该模型将进化半月板处的不均匀蒸发与流体和颗粒流动以及从稀释悬浮液到多孔塞的转变耦合在一起。这使我们能够确定带宽和沉积速率的浓度依赖性。总之，我们的研究结果允许控制干燥诱导的图案作为胶体浓度和蒸发速率的函数。(C) 2015 AIP出版有限责任公司
Drying suspensions often leave behind complex patterns of particulates, as might be seen in the coffee stains on a table. Here, we consider the dynamics of periodic band or uniform solid film formation on a vertical plate suspended partially in a drying colloidal solution. Direct observations allow us to visualize the dynamics of band and film deposition, where both are made of multiple layers of close packed particles. We further see that there is a transition between banding and filming when the colloidal concentration is varied. A minimal theory of the liquid meniscus motion along the plate reveals the dynamics of the banding and its transition to the filming as a function of the ratio of deposition and evaporation rates. We also provide a complementary multiphase model of colloids dissolved in the liquid, which couples the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate flows and the transition from a dilute suspension to a porous plug. This allows us to determine the concentration dependence of the bandwidth and the deposition rate. Together, our findings allow for the control of drying-induced patterning as a function of the colloidal concentration and evaporation rate. (C) 2015 AIP Publishing LLC.