EPSRC grant GR/S30290/01

Dr. Mark Wilson

Grant Summary of project outcomes (for non-specialist audience)

The research involved state-of-the-art simulations of liquid crystalline materials. These provide a “picture” of the organisation of molecules in a liquid crystal at an atomic and molecular level. Consequently, researchers are able to understand from the simulations how molecules organise themselves in a liquid crystal phase and how the interactions between molecules lead to specific properties of a liquid crystal.

The simulations allow us to be able to understand how molecules are arranged in a new class of bent-core molecules, which form a “biaxial” nematic phase. This phase has been controversial for around 20 years, with many claims for discovery over that period, all of which have been proved false, until the discovery of the materials studied in this grant. The new molecules have a “bend” in the centre of the rigid core and we are able to show, in the simulations, that it is the bend together with a dipole across the core of the molecule, which is responsible for the “biaxial” ordering. Biaxial phases formed from low molecular weight materials, such as these “bent core molecules”, are particularly exciting because they have the possibility of being used in electro-optic applications. The switching of molecules around the second (“short”) axis will be considerably quicker than normal switching, giving hope for far faster displays and many new applications for liquid crystal materials.

The simulation results have also been used to provide a computational route to the prediction of some of the key material properties of liquid crystals (rotational viscosities and flexoelectric coefficients). These determine how well liquid crystal materials behave in practical applications such as displays and adaptive optics for instruments such as telescopes etc. The theoretical method described in the grant, look extremely promising in terms of the ability of researchers in the future to look at how molecular interactions lead to specific bulk properties in a liquid crystalline phase. This opens up the future possibility of “molecular engineering” of new materials, using a knowledge of how molecular interactions influence material properties to design new materials.