It sounds like an easy-to-follow recipe from the world of molecular gastronomy: Dissolve nanoparticles in liquid crystals and cool to form frothy nanofoams, tiny tubes and hollow microspheres.
But what fifth-year doctoral student Sheida Riahinasab and physics Professor Linda Hirst actually discovered is a simple method for producing hollow, microscopic structures — a patent-pending process that may lead to tiny sensors, batteries and medicine-delivery systems. The work is detailed in a paper in Nature Communications, available now.
“There are many ways to make hollow microstructures in chemistry,” Riahinasab said. “But our mechanism for creating template-free hollow structures in liquid crystals is entirely novel.”
Most of us have heard of liquid crystals. They’re the LC in LCD — the technology behind most TVs, monitors and digital displays. But many of us don’t know why liquid crystals are useful to materials experts like Riahinasab and Hirst.
As the name suggests, LCs can behave as either liquid or crystal under different conditions — conditions that scientists can easily modulate.
At higher temperatures, LCs behave like liquids. The molecules flow like water and dissolve nanoparticles in much the same way H2O dissolves salt. At lower temperatures, they behave like crystals — molecules arranged in 3D grids that form a larger, rigid structure.
But what makes LCs unique is their nematic phase, a state in between liquid and crystal. The molecules are free to flow like a liquid, but exhibit order and alignment like a crystal. And nematic LCs are also bad solvents, a property that proved useful for the researchers.
