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This Communication reports that needle-like supercrystalline colloidal particles can be synthesized through anisotropy-driven self-assembly of 1,12-dodecanediamine-functionalized CdSe/CdS core/shell nanorods. The resulting superparticles exhibit both 1D lamellar and 2D hexagonal supercrystalline orders along directions parallel and perpendicular to the long axis of constituent nanorods, respectively. Our results show that the needle-like superparticles can be unidirectionally aligned through capillary forces on a patterned solid surface and further transferred into macroscopic, uniform, freestanding polymer films, which exhibit strong linear polarized PL with an enhanced polarization ratio, and are useful as energy down-conversion phosphors in polarized LEDs.

This communication reports a shape-controlled synthesis of colloidal superparticles (SPs) from iron oxide nanocubes. Our results show that the formation of SPs is under thermodynamic control and that their shape is determined by Gibbs free energy minimization. The resulting SPs adopt a simple-cubic superlattice structure, and their shape can be tuned between spheres and cubes by varying the relative free energy contributions from the surface and bulk free energy terms. The formation of sphere-shaped SPs from nanocubes suggests that the size-dependent hydration effect predicted by the Lum–Chandler–Weeks theory plays a very important role in the self-assembly of nano-objects. In addition, the iron oxide SPs exhibit shape-dependent therapeutic effects in magnetomechanical treatments of cancer cells in vitro.