Nanojewels made easy(structures that naturally form ordered s...)

Superhydrophobic surfaces allow nanojewels to be created from a single drop of water containing nanoparticles, because of several effects.

First, the drop stays in the shape of a ball because water does not spread on it while the nanoparticles are held in the drop due to the surface tension of water.

Compared to drying the drop in air, which is a fast evaporation process that causes the water in the drop to distort and flow, the drop gently dries on the superhydrophobic surface. This lets the nanoparticles get as close to each other as possible, swirling in a slow circular motion until all of the water evaporates.

When nanoparticles of two different sizes are used in the same drop, the smaller ones move to the surface of the drop while the bigger ones stay in the middle. This is because the smaller ones have more Brownian motion and are elevated to the surface with the water molecules that are subsequently evaporating at the surface, leaving all of the nanoparticles behind to form the nanojewels.

"Besides the dazzling look of these nanojewels, the most exciting thing about this work is that it opens up many interesting possibilities in quickly and inexpensively making new materials with nanoparticles", Marquez says.

"By understanding how different particle sizes determine the colors produced, these nanojewels can be designed for applications in optical communication systems," Melle adds.

As more nanoparticles and nanostructures come into the marketplace, technologies that can quickly assemble the structures so that their unique size and properties can be employed in new devices will be important to the growth of nanotechnology and related industries.

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