Home > Uncategorized > Electric dipoles and phase stability in nematic liquid crystals

Electric dipoles and phase stability in nematic liquid crystals

May 9th, 2010

A. G. Vanakaras and D.J. Photinos, Mol. Phys., 85(6), 1089-1104 (1995).

Abstract: A theory for the nematic-isotropic (N-I) phase transition of prolate uniaxial molecules with longitudinal dipole moments is presented. The theory is based on the variational cluster expansion, truncated after the two-molecule term, and is implemented for polar hard spherocylinders with and without attractions, and for polar linear arrays of Lennard-Jones interaction centres. We find that the dipole interactions substantially shift the N-I transition temperature and strongly promote antiparallel molecular association, but have a weak effect on the order parameters, the pressure, and the N-I coexistence densities. The effect of dipoles on phase stability is very sensitive to their position within the molecular frame. Off-centre dipoles are shown to give rise to phase re-entrance according to the sequence N-I-N on heating at constant density. The theory does not predict a stable ferroelectric nematic phase.

Categories: Uncategorized Tags:
Comments are closed.