Engineered Anisotropic Fluids of Rare Earth Nanomaterials.

The self-assembly of inorganic nanoparticles into well-ordered structures in the absence of solvents is generally hindered by van der Waals forces, leading to random aggregates between them. To address the problem, we functionalized rigid rare earth (RE) nanoparticles with a layer of flexible polymers by electrostatic complexation. Consequently, an ordered and solvent-free liquid crystal (LC) state of RE nanoparticles was realized. The RE nanomaterials including nanospheres, nanorods, nanodiscs, microprisms and nanowires all show a typical nematic LC phase with one-dimensional orientational order, while their microstructures strongly depend on the particles' shape and size. Interestingly, the solvent-free thermotropic LCs possess an extremely wide temperature range from -40 °C to 200 °C. The intrinsic ordering and fluidity endow anisotropic luminescence properties in the system of shearing-aligned RE LCs, offering potential applications in anisotropic optical micro-devices.