Facile self-assembly of colloidal diamond from tetrahedral patchy particles via ring selection

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 48; pp. 1 - 7
• Main Authors: Neophytou, Andreas, Chakrabarti, Dwaipayan, Sciortino, Francesco
• Format: Journal Article
• Language: English
• Published: Washington National Academy of Sciences 30.11.2021
• Subjects: Clathrates; Colloids; Crystal lattices; Crystal structure; Crystallization; Crystals; Diamonds; Fabrication; Photonic crystals; Physical Sciences; Self-assembly
• ISSN: 0027-8424; 1091-6490
• 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.