Donaldson Joe G, Schall Peter, Rossi Laura
Department of Chemical Engineering, Delft University of Technology, 2629 HZ Delft, The Netherlands.
Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.
ACS Nano. 2021 Mar 23;15(3):4989-4999. doi: 10.1021/acsnano.0c09952. Epub 2021 Mar 2.
Manipulating the way in which colloidal particles self-organize is a central challenge in the design of functional soft materials. Meeting this challenge requires the use of building blocks that interact with one another in a highly specific manner. Their fabrication, however, is limited by the complexity of the available synthesis procedures. Here, we demonstrate that, starting from experimentally available magnetic colloids, we can create a variety of complex building blocks suitable for hierarchical self-organization through a simple scalable process. Using computer simulations, we compress spherical and cubic magnetic colloids in spherical confinement, and investigate their suitability to form small clusters with reproducible structural and magnetic properties. We find that, while the structure of these clusters is highly reproducible, their magnetic character depends on the particle shape. Only spherical particles have the rotational degrees of freedom to produce consistent magnetic configurations, whereas cubic particles frustrate the minimization of the cluster energy, resulting in various magnetic configurations. To highlight their potential for self-assembly, we demonstrate that already clusters of three magnetic particles form highly nontrivial Archimedean lattices, namely, staggered kagome, bounce, and honeycomb, when focusing on different aspects of the same monolayer structure. The work presented here offers a conceptually different way to design materials by utilizing preassembled magnetic building blocks that can readily self-organize into complex structures.
控制胶体颗粒的自组装方式是功能性软材料设计中的核心挑战。应对这一挑战需要使用能以高度特定方式相互作用的构建单元。然而，它们的制造受到现有合成程序复杂性的限制。在此，我们证明，从实验可得的磁性胶体出发，我们可以通过一个简单的可扩展过程创建各种适合层级自组装的复杂构建单元。利用计算机模拟，我们在球形约束条件下压缩球形和立方体形磁性胶体，并研究它们形成具有可重复结构和磁性特性的小簇的适用性。我们发现，虽然这些簇的结构具有高度可重复性，但其磁性特征取决于颗粒形状。只有球形颗粒具有产生一致磁性构型的旋转自由度，而立方体形颗粒阻碍了簇能量的最小化，导致了各种磁性构型。为突出它们的自组装潜力，我们证明，当关注同一单层结构的不同方面时，仅由三个磁性颗粒组成的簇就能形成高度复杂的阿基米德晶格，即交错的 Kagome 晶格、弹跳晶格和蜂窝晶格。本文所展示的工作提供了一种概念上不同的材料设计方法，即利用可轻易自组装成复杂结构的预组装磁性构建单元。
