Title: Entropy driven assembly of colloidal tetrahedra into diamond structure

Author (Talk): Zhe Gong, New York University

Abstract:

Building blocks with non-trivial shape are thought to bear invaluable information that largely determines both pathway and final product in self-assembly system. Packing of polyhedra leads to a large diversity of hierarchical structures, among which tetrahedra with various degrees of truncation have been of particular interest due to its unique symmetry. However, the experimental realization of colloidal tetrahedra remains challenging. Here for the first time, surface tension assisted by geometric constraints is used to synthesize truncated colloidal tetrahedra via colloidal fusion, with high size and morphology regularity. The entropy driven assembly of truncated tetrahedral particles was carefully studied via depletion interaction and sedimentation. In both cases, particles exhibit strong face-to-face contact tendency induced by directional entropic force, leading to hexagonal and cubic diamond structures. This study provides information about shape-structure relationship in the packing of truncated tetrahedra, and may further enhance the understanding of crystallization of diamond and its stacking hybrid.