The birefringence technique has been used for the evaluation of order parameter in the nematic phase along with the density measurements, which are needed for the calculation of molecular polarizabilities of the compounds. Birefringence and density studies have been carried out on the three liquid crystalline compounds viz.(1) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-butoxybenzoate (2) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(decycloxy)benzoate and (3) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(tridecycloxy)benzoate. Using birefringence and density data the molecular polarizabilities are evaluated by two different internal field models due to Vuks and Neugebauer. The mean molecular polarizability of the compounds is also evaluated by employing modified Lippincott δ-function model. The results reveal that both the theoretical and experimental values obtained are very near to each other.
In this work, gold and silver nanoparticles are separately dispersed in n-hexyloxy-cyanobiphenyl (6O.CB) liquid crystal in the ratio 1:100. The optical textures of pure and nano-dispersed compounds are recorded by using polarizing optical microscope. Differential scanning calorimeter (DSC) is used to compute enthalpy and transition temperature values. Due to the dispersion of nanoparticles, the clearing temperature of the compounds are slightly reduced but there is no significant change in the nematic phase exhibited by pure 6O.CB. Further characterization is done by various spectroscopic techniques like scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical textures have been analyzed using MATLAB software for the evaluation of display parameters viz., Luminance, Luminance coefficient, Luminance uniformity and Contrast ratio.
The transition temperatures of Cyano-biphenyl liquid crystalline compounds, (12.CB, 7O.CB and 5O.CB) are recorded by using Differential scanning calorimeter. The transition temperatures are used to estimate molecular polarizability by theoretical approaches, i.e., by Lippincott-delta function technique and molecular vibration technique. The density and refractive indices are measured by using specially designed Pyknometer and indigenously developed spectrometer coupled with small angled prism. The molecular polarizabilities are assessed by Vuks and Neugebauer methods using experimentally obtained refractive indices and density data. The results obtained by the current techniques and their limitations are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.