Customizable nano-sized colloidal tetrahedra by polymerization-induced particle self-assembly (PIPA)†
Colloidal molecules (CMs) are colloidal clusters with molecule-like symmetry and architecture, generated from the self-assembly of nanoparticles with attractive patches. However, the large-scale preparation of patchy nanoparticles remains challenging. Here, we synthesize CH4-like colloidal tetrahedra (CTs) in a scalable way by aqueous polymerization-induced particle self-assembly (PIPA), where isotropic diblock copolymer spheres are used as seeds. During PIPA, the newly formed third block aggregates into attractive patches, which bridge the isotropic spheres together to form CTs in situ, as a result of surface energy minimization. This approach surpasses previous reports in its scalability, high yield and versatility. For example, the purity of as-prepared CTs reaches 78.3% at a concentration of 100 g L−1, which allows the 3D reconstruction of the tetrahedral structure by single particle electron microscopy analysis. The versatility of PIPA is illustrated by preparing CMs of tunable size, valency and various chemical structures. In addition, the architecture of the CMs can be manipulated after the PIPA process simply by the addition of ethanol, for example, the CTs can be transformed into ladder-like structures, paving a new avenue to access hierarchical nanoscale self-assemblies.