Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping
Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping
复制标题
Janus 粒子掺杂剪切负载粒子流体界面的非均相动力学
DOI：
10.1021/acs.langmuir.3c01085
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发表时间：
2023
期刊：
影响因子：
3.9
通讯作者：
Cheng, Xiang
中科院分区：
文献类型：
--
作者：
Qiao, Yiming;Liu, Zhengyang;Ma, Xiaolei;Keim, Nathan C.;Cheng, Xiang
颗粒团簇的形成可以显著改变悬浮液在二维和三维中的动力学和机械性质。虽然它已被公认，大的网络跨越集群增加刚性的颗粒系统，它仍然不清楚如何本地化的nonpermeating集群的存在影响颗粒悬浮液的动力学和机械性能。在这里，我们介绍了自组装的局部粒子簇在流体-流体界面混合的Janus粒子的一部分，在一个单层的均匀胶体。每个Janus粒子与附近的一些均匀胶体结合，导致许多小的簇均匀分布在界面上。使用定制的磁棒界面应力流变仪，我们施加线性振荡剪切的颗粒负载的流体界面。通过分析从光学显微镜的粒子的局部仿射变形，我们表明，在本地集群中的粒子经历大幅降低剪切诱导的拉伸比他们的邻居以外的集群。我们假设，这种异质动力学引起的颗粒簇增加了有效的表面覆盖的颗粒，这反过来又提高了界面的剪切模量，证实了直接的界面流变测量。我们的研究说明了剪切流中的小集群的微观动力学，并揭示了它们的深刻影响的宏观流变学的颗粒负载的流体界面。我们的研究结果开辟了一条途径，通过控制局部颗粒簇的形成，设计具有改善的机械性能的界面材料。
The formation of particle clusters can substantially modify the dynamics and mechanical properties of suspensions in both two and three dimensions. While it has been well established that large network-spanning clusters increase the rigidity of particle systems, it is still unclear how the presence of localized nonpercolating clusters affects the dynamics and mechanical properties of particle suspensions. Here, we introduce self-assembled localized particle clusters at a fluid–fluid interface by mixing a fraction of Janus particles in a monolayer of homogeneous colloids. Each Janus particle binds to a few nearby homogeneous colloids, resulting in numerous small clusters uniformly distributed across the interface. Using a custom magnetic rod interfacial stress rheometer, we apply linear oscillatory shear to the particle-laden fluid interface. By analyzing the local affine deformation of particles from optical microscopy, we show that particles in localized clusters experience substantially lower shear-induced stretching than their neighbors outside clusters. We hypothesize that such heterogeneous dynamics induced by particle clusters increase the effective surface coverage of particles, which in turn enhances the shear moduli of the interface, as confirmed by direct interfacial rheological measurements. Our study illustrates the microscopic dynamics of small clusters in a shear flow and reveals their profound effects on the macroscopic rheology of particle-laden fluid interfaces. Our findings open an avenue for designing interfacial materials with improved mechanical properties via the control of formation of localized particle clusters.