Colloid Chemistry , University of Konstanz , Universitaetsstrasse 10 , 78464 Konstanz , Germany.
Langmuir. 2018 Nov 6;34(44):13339-13351. doi: 10.1021/acs.langmuir.8b02999. Epub 2018 Oct 23.
Understanding the hydrodynamics of colloids with complex shapes is of equal importance to widespread practical applications and fundamental scientific problems, such as gelation, crystallization, and phase behavior. Building on previous work, we present a comprehensive study of sedimentation, diffusion, intrinsic viscosities, and other shape-dependent quantities of clusters built from spherical nanoparticles. Cluster preparation is accomplished by assembling surface-modified polystyrene particles on evaporating emulsion droplets. This results in supracolloids that exhibit well-defined configurations, which are governed by the number of constituent particles. Sorting into uniform cluster fractions is achieved through centrifugation of the cluster mixture in a density gradient. Sedimentation coefficients are elucidated by differential centrifugal sedimentation. Rotational and translational diffusion of the clusters are investigated by polarized and depolarized dynamic light scattering. The experimental results are compared to data obtained via a bead-shell model suitable for predicting hydrodynamic quantities of particles with arbitrary shapes. The experimental data are in excellent agreement with the predictions from hydrodynamic modeling. The variety of investigated shapes shows the robustness of our approach and provides a complete picture of the hydrodynamic behavior of complex particles.
理解具有复杂形状的胶体的流体动力学对于广泛的实际应用和基础科学问题都同等重要，例如胶凝、结晶和相行为。基于之前的工作，我们对由球形纳米颗粒构建的聚集体的沉降、扩散、固有粘度和其他依赖形状的量进行了全面研究。通过在蒸发乳液液滴上组装表面修饰的聚苯乙烯颗粒来制备聚集体。这导致了具有明确定义的结构的超胶体，这些结构由组成颗粒的数量决定。通过在密度梯度中对聚集体混合物进行离心分离，可以实现均匀聚集体分数的分离。通过差速离心沉降来阐明沉降系数。通过偏振和非偏振动态光散射研究聚集体的旋转和平移扩散。将实验结果与通过适合预测具有任意形状的颗粒的流体力学量的珠壳模型获得的数据进行比较。实验数据与流体力学建模的预测非常吻合。所研究的各种形状显示了我们方法的稳健性，并提供了复杂颗粒流体动力学行为的完整图像。
