Dipole Association of Polar Mesogens in a Liquid Crystal Solvent

Abstract

This paper reports results of a detailed examination of the low frequency dielectric properties of dilute anisotropic solutions of two polar mesopens, 4-cyano-3-fluorophenyl-4′-propylbenzoate(C3FCN) and 4-cyanophenyl-4′-butylbenzoate(C4CN), as solutes in a non-polar liquid crystal solvent. At low concentrations the effects of dielectric weening are minimised. and the association of mesogens due to dipole-dipole forces can be studied. The measurements suggest that at very low concentrations the dipole-dipole interactions result in a small increase in the effective dipole moment. while at higher concentrations local antiferroelectric order becomes dominant. The results are fitted to an association model, which was originally developed to describe the dielectric behaviour of isotropic solutions of polar solutes (alcohols) in carbon tetrachloride solutions.

Key Words:

• Liquid crystals
• dielectric properties
• dipole correlation