optical studies on liquid crystals with dispersed zno nanoparticles

Abstract

ZnO nanoparticles (ZnOnps) have wide range of applications and improve the optical parameters of molecules of soft liquid crystalline (LC) materials. The present work mainly discusses the optical studies on LC materials regarding p-Alkoxybenzoic acids (noba, n = 3 and 4), p- Alkylbenzoic acids (nba, n = 3 and 4) and p-Octyloxy- p - cyanobiphenyl (8ocb) compound along with homogeneous dispersion of ZnOnps in lower weight concentrations i.e., 1, 1.5, 2 and 2.5 wt%. The ZnOnps are synthesized by standard process using high pressure Autoclave. The well synthesized ZnOnps dispersed homogeneously with different concentrations (1 - 2.5 wt%) separately in the given LC compounds with the aid of magnetic stirrer and sonicator bath with proper procedure. The characterization studies on LCs with dispersed ZnOnps in various concentrations are done by various experimental techniques such as UV-Visible spectroscopy (UV-Vis), Scanning electron microscopy (SEM), X-ray Diffraction (XRD), Polarising optical microscopy (POM), Differential scanning calorimeter (DSC), Modified spectrometer and Homomorphic filtering technique- MATLB tool. The UV-Vis spectroscopy is used to determination of the presence of ZnOnps in the LC compound and is confirmed by corresponding peak at 250 nm. SEM is used to determine the thickness of ZnOnps dispersed in LC compounds and the elementary data with its atomic weight percentage through Energy Dispersive Spectra (EDS). The existence of ZnOnps in LC compounds is well determined through X-ray diffraction and grain size of ZnOnps is well determined through Scherrer s formula. The textures of LC phases along with phase transition temperatures are determined by using POM. The Homomorphic filtering technique is used to improve the quality of the textures of LCs and its ZnO nanocomposites at the newline newlinephase transitions by eliminating the low frequency (noise) components. The LC phase transition temperatures and corresponding enthalpy values are determined through DSC.