Producing and patterning of nanocrystals using “atto-incubators” composed of the core-shell particles

We developed a small incubator of an atto-liter scale (atto-incubator) for producing and arraying nanosized materials. The core-shell particles with a hydrogel shell were used as an incubator to isolate individual droplets of the solution and to specify the nucleation sites for crystallizing NaCl and urea solutes. Their array was deposited on a polystyrene dish by the spin-coating of a particulate dispersion, and then dried to remove any residual solvent. When the array was exposed to a solution, the hydrogel shell absorbed the solution and swelled. Nucleation of the nanocrystals at the particles occurred as the arrays were dried again. We obtained single crystals as a rectangular solid with a uniform shape at 8 wt.% NaCl. By the use of atto-incubators for urea crystallization, we obtained nanosized fibers of a single crystal, which were aligned in the direction of the flow. The atto-incubator could allow us to control the nucleation region and the size and shape of the crystals.