An Optical Study to Estimate Orientational Order Parameter on Some Benzylideneaminophenylbenzoate Liquid Crystals

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 delta-function model. The results reveal that both the theoretical and experimental values obtained are very near to each other.