Feng Yijun, Wang Lin, Xu Jinliang, Liu Guohua
Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing, 102206, P. R. China.
Soft Matter. 2022 Jul 20;18(28):5230-5238. doi: 10.1039/d2sm00506a.
The robust attachment of particles at fluid interfaces is favorable for engineering new materials due to the large capillary energy, but it meets significant challenges when particle removal is a requirement. A previous study has shown that soap films can be utilized to achieve particle separation from liquid marbles. Here, we investigate the effects of particle size on the particle separation from liquid marbles using fast dynamics of drop impact on a soap film. Experimental observations disclose that the fast dynamics of the liquid marble involves coalescence, bouncing, stripping, or tunneling through the film by controlling the falling height and drop volume. More importantly, the active regime of the stripping mode can be selective-controlled by tuning the particle size, and the smaller stabilizing particles make a wider stripping regime. This is attributed to the smaller change of the surface energy resulting from the larger surface tension of LMs wrapped by smaller particles. Theoretical analysis reveals that the stripping thresholds are determined by the energy competition between kinetic energy, the increased surface energy and viscous dissipation, which offers important insights into particle separation by tuning the particle size. The present study provides guidelines for applications that involve phase separation.
由于具有较大的毛细能量，颗粒在流体界面处的牢固附着有利于新型材料的工程应用，但当需要去除颗粒时，这会面临重大挑战。先前的一项研究表明，肥皂膜可用于实现液体弹珠中颗粒的分离。在此，我们利用液滴撞击肥皂膜的快速动力学，研究了颗粒尺寸对从液体弹珠中分离颗粒的影响。实验观察表明，通过控制下落高度和液滴体积，液体弹珠的快速动力学过程包括聚并、弹跳、剥离或穿过薄膜的隧穿。更重要的是，剥离模式的活跃状态可通过调整颗粒尺寸进行选择性控制，较小的稳定颗粒会产生更宽的剥离区域。这归因于被较小颗粒包裹的液体弹珠具有较大表面张力，导致表面能变化较小。理论分析表明，剥离阈值由动能、增加的表面能和粘性耗散之间的能量竞争决定，这为通过调整颗粒尺寸进行颗粒分离提供了重要见解。本研究为涉及相分离的应用提供了指导。
