Thermotropic liquid crystal doped with silica, silica grafted with aniline (ANI@SiO2) and polyaniline (PANI@SiO2)

Abstract

Nanoparticles dispersed in liquid crystals exhibit novel and intriguing properties, which make them suitable materials for displays and photonic applications. This paper reports on the impact of non-modified silica (SiO2), silica grafted with aniline (ANI@SiO2) and silica grafted with polyaniline (PANI@SiO2) nanoparticles on the physical parameters of 7CB liquid crystal. A slight change in the nematic-isotropic phase transition temperature was observed. The results from dielectric experiments revealed an increase in free ion concentration in the doped samples. By fitting a suitable equivalent electric circuit model to the experimental data, we demonstrate changes in the electro-physical parameters of the liquid crystal in the bulk and at the liquid crystal-metal electrode interface. Therefore, we were able to calculate the ion mobility and the diffusion constant. It was also demonstrated that the doping of 7CB with the above-mentioned nanoparticles increases the response time, thresholds, and viscosity.