TCD Led Research Reveals New Property of Liquid Crystals

Posted on: 20 October 2010

New collaborative research, conducted by Professor of Electronic Materials, Jagdish K Vij, of TCD’s School of Engineering, has revealed a new property of liquid crystals (LC’s) which mean further possibilities for these already widely used materials.  The findings were recently published in the October 16th issue of the leading scientific journal Physical Review Letters and detail how the scientists were able to control the appearance of the periodic patterns of the LC’s thereby discovering a new liquid crystalline phase.

Liquid crystals are a state of matter which possess properties both of liquid, giving them the ability to flow, as well as of a solid crystal, displaying order and anisotropy.  Because of their unique physical properties liquid crystals are commonly used in the electronic displays of computers, televisions, cell phones and portable gaming devices.  This new research reveals a novel type of liquid crystalline nematic phase, where molecules start self-assembly at a nano-level and form unusual periodic domains at the microscopic level when confined in between two specially treated glass plates, a phenomenon never observed before.  The major advantage with this new discovery is that the molecules self-assemble into periodic structures spontaneously without the need for external stimuli.

Liquid molecules self-assembly at nano-scale.

One of the most common phases of a liquid crystal is the nematic phase which derives its name from the thread like optical textures exhibited by the rod-shaped organic molecules of the liquid crystals.  These molecules are free to flow like those of a conventional liquid and although they have no positional order, they self-align to have long range directional order with their long axes roughly parallel to each other.  This long range directional order provides the material with different properties when observed from different directions, the most significant of which are the optical properties, making them extremely useful in liquid crystal displays.

To date, nematic liquid crystals resist certain deformations.  The novel materials on the other hand, although belonging to the class of nematic liquid crystals, develop microscopic periodic patterns causing a deformation in the classical uniform structure of the crystal.  Analysing the deformations, the scientists derive a simple theory which proposes another type of nematic phase for liquid crystals which could prove to have fascinating applications in condensed matter science and technology.  Moreover the discovery has the potential to widen the field of applications of liquid crystals towards 3D displays and novel types of photonic devices.   Currently the worldwide market for displays and photonic devices using liquid crystals is valued at $900 billion and this research could result in Ireland and the EU taking a leading position in this market.

The leading researchers in the group who discovered this phenomenon are TCD scientists Dr Vitaly P Panov, Mamatha Nagaraj and Dr Yury Panarin of the Dublin Institute of Technology.  The collaborating team who have synthesised these advanced materials are from the research group of Dr George Mehl of the University of Hull’s Department of Chemistry.  The teams were funded by FP-7 EU project on Biaxial Nematic Devices (BIND).