The Temperature Dependence of Static Dielectric Permittivities and Dipole Moments of Two Mesogens and their Mixture

Abstract

The compounds p-pentylphenyl-2-chloro-4-(p-pentylbenzoyloxy)-benzoate and p-octyl-phenyl-2-chloro-4-(p-heptylbenzoyloxy)-benzoate and their mixture (1:1 mole fraction) show nematic phases with supercooling effect below room temperature. Molecular dipole moments μ of the compounds have been determined by solution method. The static dielectric constants ϵ and ϵ_⊥ have been measured as functions of temperature at a frequency of 10 kHz. Mesogenic molecular dipole moments μ and their inclination angles β with the molecular long axis are determined following Maier and Meier equations. Short range antiferroelectric order is found to exist in the nematic phase. Kirkwood correlation factors have also been calculated.

Key Words:

• nematic phenyl benzoates
• dielectric constants
• dipole moments
• dipole correlation factors