Chemists get custom-designed microscopic particles to self-assemble in liquid crystal

"We're learning the rules about how these lithographic particles self-assemble," said Thomas G. Mason, a UCLA professor of chemistry and physics and a member of the California NanoSystems Institute at UCLA. "This method may enable us to cause them to assemble in desired configurations." "We're examining how pairs of particles interact and come to attach together," Mason said. "If we can get the particles to interact in certain controlled ways, we can build larger-scale assemblies that may have applications in photonics, optical communication networks and a variety of other areas." Mason and his colleagues — lead author Clayton Lapointe, a postdoctoral scholar at UCLA, formerly at the University of Colorado at Boulder, and Ivan Smalyukh, an assistant professor of physics at the University of Colorado at Boulder — used an optical microscope to study the attractions between the particles, which they custom designed in various shapes, including triangles, squares and pentagons. The particles are too small to see with the unaided eye but are quite clear with the instrument. "This is a very complex material that we have created," said Mason, whose research is at the intersection of chemistry, physics, engineering and biology. "We have made lithographic particles dispersed in a liquid crystal, and the molecular constituents are aligned." Particles of different shapes interact in different ways, Lapointe, Mason and Smalyukh report. Those with an odd number of sides, such as triangles and pentagons, interact differently than particles shaped like squares.