Neophytou Andreas, Chakrabarti Dwaipayan, Sciortino Francesco
School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
Proc Natl Acad Sci U S A. 2021 Nov 30;118(48). doi: 10.1073/pnas.2109776118.
Diamond-structured crystals, particularly those with cubic symmetry, have long been attractive targets for the programmed self-assembly of colloidal particles, due to their applications as photonic crystals that can control the flow of visible light. While spherical particles decorated with four patches in a tetrahedral arrangement-tetrahedral patchy particles-should be an ideal building block for this endeavor, their self-assembly into colloidal diamond has proved elusive. The kinetics of self-assembly pose a major challenge, with competition from an amorphous glassy phase, as well as clathrate crystals, leaving a narrow widow of patch widths where tetrahedral patchy particles can self-assemble into diamond crystals. Here we demonstrate that a two-component system of tetrahedral patchy particles, where bonding is allowed only between particles of different types to select even-member rings, undergoes crystallization into diamond crystals over a significantly wider range of patch widths conducive for experimental fabrication. We show that the crystallization in the two-component system is both thermodynamically and kinetically enhanced, as compared to the one-component system. Although our bottom-up route does not lead to the selection of the cubic polytype exclusively, we find that the cubicity of the self-assembled crystals increases with increasing patch width. Our designer system not only promises a scalable bottom-up route for colloidal diamond but also offers fundamental insight into crystallization into open lattices.
具有金刚石结构的晶体，特别是那些具有立方对称性的晶体，长期以来一直是胶体颗粒程序化自组装的诱人目标，因为它们可作为能够控制可见光传播的光子晶体。虽然以四面体排列方式装饰有四个斑块的球形颗粒——四面体斑块颗粒——应该是实现这一目标的理想构建块，但事实证明，它们自组装成胶体金刚石的过程难以捉摸。自组装动力学构成了一项重大挑战，存在来自无定形玻璃相以及笼形晶体的竞争，使得四面体斑块颗粒能够自组装成金刚石晶体的斑块宽度范围很窄。在此，我们证明了一种由四面体斑块颗粒组成的二元体系，其中仅允许不同类型的颗粒之间形成键合以选择偶数元环，在有利于实验制备的显著更宽的斑块宽度范围内会结晶成金刚石晶体。我们表明，与一元体系相比，二元体系中的结晶在热力学和动力学上都得到了增强。尽管我们的自下而上方法并非专门导致立方多型的选择，但我们发现自组装晶体的立方度会随着斑块宽度的增加而提高。我们设计的体系不仅有望为胶体金刚石提供一种可扩展的自下而上途径，还能为开放晶格的结晶提供基本见解。
