Dipole-Dipole Association of Polar Molecules in a Non-Polar Liquid Crystal Solvent

Abstract

Measurements are reported of the permittivity as a function of temperature and composition for strongly dipolar cyano-substituted molecules dissolved in a non-polar nematic liquid crystal solvent. Solute molecules with dipole moments perpendicular to the molecular alignment axes exhibited strong parallel association of their dipoles, even at low concentrations, and the measurements can be interpreted in terms of a ‘strong dimer’ model. Results for a solute molecule with a large dipole moment co-linear with the long molecular axis gave the major dipole correlation factor equal to 1, consistent with little or no preferred dipole-dipole correlation.

Key Words:

• dipole-dipole association
• nematic
• transverse dipole
• dielectrics