Order Parameter Studies by Image Analysis

In this paper, Thermo optical properties of two azomethine liquid crystals: 3-hydroxy-4-{[(4iodophenyl)imino]methyl}phenyl alkanoates (Cn-1H2n-1COO-, n = 8,18) comprising terminal iodo substituent are investigated using image analysis technique in conjunction with Optical Polarizing Microscope. This investigation purely based on intensities of the liquid crystal textures as a function of temperature. Thermo optical properties: Optical transmittance, Absorption coefficient, Birefringence, Phase retardation and Order parameter of the liquid crystals are computed by analyzing the textures of liquid crystals using MATLAB software. The obtained results show that, the length of terminal chain length influences the thermo optical properties of the compounds. The lowest member of the azomethine liquid crystals: nABIA (n = 8), with respect to temperature exhibited the tunable birefringence by showing more variations in the birefringence values of each wavelength with linearity compared to the highest member nABIA (n= 18) and the azomethine liquid crystal where n = 8 is more suitable for applications than the compound (n = 18).