Study of Mesomorphic Properties of Three Alkenyl Liquid Crystalline Compounds

Abstract

We have undertaken the study of the physical properties e.g. density, optical birefringence and x-ray diffration of three liquid crystalline compounds having bicyclohexane rigid core and isolated C=C double bond in the chain. The physical properties of these liquid crystals are strongly affected by the positional changes of the double bond. We have measured the refrative indices (n_o, n_e) for three diffarent wavelengths and calculated the polarizability values, (α_o, α_e) different temperatures. It is found that for all the compounds optical birefringence is very low (Δn < 0.1). We have also calculated the intermolecular distance, pseudo layer spacing, correlation length and the orientational order parameter values at different temperatures from low angle x-ray diffraction photographs of aligned samples. Orientational order parameters at different temperatures were calculated both from birefrigence and x-ray study.