Dependence of physical parameters on the size of silver nano particles forming composites with a nematic liquid crystalline material

Abstract

Thermodynamic, dielectric and electro-optical properties of a nematic liquid crystal namely 4-(trans-4-nhexylcyclohexyl) isothiocyanatobenzoate (6CHBT) mixed with silver nanoparticles (Ag-NPs) of two widely different sizes have been studied. Thermodynamic studies suggest nominal increase in isotropic to nematic transition temperature of the nano composites as compared to the pure 6CHBT. Dielectric parameters of nano composites in the homeotropic and planar aligned samples have been measured in the frequency range of 1 Hz–35 MHz. Dielectric studies suggest that anisotropy is marginally decreased due to the dispersion of Ag-NPs. Threshold voltage for Freedericksz transition and splay elastic constant has decreased in the case of nano composites. Dielectric studies also suggest that relaxation mode corresponding to the molecular rotation about its long axis cannot be detected in the experimental window of the frequency.However, we obtained a relaxation mode due to the molecular rotation about its short axis.