Researchers Find Geometric Shape Can Control Order in Liquid Crystals

Scientists have found a method to control liquid crystals using tiny nanometer- and micrometer-sized particles with different geometric shapes. 

This technology could help manufacturers and engineers develop new uses for liquid crystals, which we currently use in LCD (liquid crystal display) television and computer monitors, tunable lenses and muscle-like actuators, to name a few items.

Liquid crystals can act like ordered solids and flowing liquids, depending on how the crystal molecules align. Scientists can manipulate the orientation of the molecular rods with electric, optical, magnetic or mechanical forces, making liquid crystals great for use in many devices.

Ivan Smalyukh, a professor at the University of Colorado at Boulder, added precisely shaped particles made of polymers, gold, and other materials to observe the organization of the liquid crystal molecules and the assembly of the particles controlled by light and electric fields. 

Specifically, graduate students Angel Martinez, Julian Evans, Rahul Trivedi, and Paul Ackerman and postdoctoral associates Clayton Lapointe and Bohdan Senyuk of the University of Colorado added particles shaped like spheres, rods, triangles, rings, squares, pentagons, and hexagons to a liquid crystal and watched as these exceedingly small objects produced well-defined changes in the alignment of the liquid crystal. Faceted plates and rods with an even number of sides influenced the liquid crystal in a symmetric fashion, while triangles and pentagons distorted the alignment of rod-like molecules along a defined direction. This allowed the scientists to use liquid crystals as smart fluids to assemble particles into desired structures controlled by light and fields, like the labirynth shown on the optical micrograph taken by Angel Martinez.

The research means we can engineer new properties into the liquid crystals, possibly leading to new or improved technologies and applications.