University of Warwick scientists have shown how to tie knots in liquid crystals using a miniature Möbius strip made from silica particles.
By tying substances like this in knots, the researchers hope to understand how their intricate configurations and unique properties can be harnessed in the next generation of advanced materials and photonic devices. Liquid crystal is an essential material in modern life – the flat panel displays on our computers, TVs and smartphones all make use of its light-modulating properties. It is composed of long, thin, rod-like molecules which align themselves so they all point in the same direction. By controlling the alignment of these molecules, scientists can literally tie them in a knot.
To do this, they simulated adding a micron sized silica particle – or colloid – to the liquid crystal. This disrupts the orientation of the liquid crystal molecules. For example, a colloid in the shape of a sphere will cause the liquid crystal molecules to align perpendicular to the surface of the sphere, a bit like a hedgehog’s spikes.
Using a theoretical model, the University of Warwick scientists have taken this principle and extended it to colloids which have a knotted shape in the form a Möbius strip. A Möbius strip with one twist does not form a knot, however with three, four and five twists it becomes a trefoil knot (like an overhand knot with the ends joined together), a Solomon’s knot or a cinquefoil knot respectively. By adding these specially designed knotted particles they force the liquid crystal to take on the same structure, creating a knot in the liquid crystal.
One of the researcher concluded: “Our research extends this previous work to apply to liquid crystal, the substance we use every day in our TVs, smartphones and computer screens.
“We are interested in this as creating and controlling these intricate knotted fields is an emergent avenue for the design of new metamaterials and photonic devices.”
This story is reprinted from material from the University of Warwick, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.