Strengthening of columnar hexagonal phase of a room temperature discotic liquid crystalline material by using ferroelectric barium titanate nanoparticles

Abstract

A discotic liquid crystalline (DLC) material possessing a wide room temperature columnar hexagonal phase has been used as a polymeric matrix to disperse ferroelectric barium titanate nanoparticles at the concentrations of 0.5 wt% and 1.0 wt% respectively. The influence of nanoparticles on the discotic liquid crystal has been studied with the help of Differential Scanning Calorimetry, impedance spectroscopy, polarizing optical microscopy and Ultraviolet-Visible spectroscopy. Small angle X-ray scattering (SAXS) measurements have also been performed. Thermal measurements reveal stabilization of the columnar hexagonal phase due to the addition of ferroelectric nanoparticles in the discotic system. Permittivity is decreasing due to the formation of anti-dipolar ordering in the presence of ferroelectric nanoparticles. A relaxation mode is visible in the high kHz to low MHz region. The relaxation frequency has been found to decrease with the incarceration of barium titanate nanoparticles in DLC. A shift in UV–Vis absorption/transmittance spectra indicates modification in the electronic structure and hence physical property of the nanocomposites. SAXS explains the variation of different hexagonal lattice parameters with respect to the temperature.