The study of mesomorphic, morphologic and electro-optic properties of liquid crystal systems

In this study, the temperature dependences of the optical transmissions and absorption coefficients for the six novel salicylaldimine based liquid crystals? direct and reverse?phase transitions have been investigated and the comparison of these dependences with the thermo-morphological properties of these reviewed materials have been accomplished. It has been observed that thermo-optical and thermotropic properties at the direct and reverse phase transitions between the liquid crystal mesophase and isotropic liquid exhibited non-linear behaviour. Thermal hysteresis has been attained for the dependence of optical transmission and absorption coefficients on the temperature. Also, it has been observed that the phase transition temperatures shift to lower values for the reverse phase transitions as compared to the ones for the direct phase transitions and also widening of the heterophase region has been noticed.The effects of the chain substitution pattern on the thermo-morphological, thermotropic and thermo-optical properties of the imine compounds have been investigated. Also, new chiral and achiral imine compounds, which were first synthesized by our group, have been compared.New salicilaldimine compounds, synthesized by our group, have been doped with 5CB and 7CB nematic liquid crystals. The dielectrical properties of the doped liquid crystals have been investigated using dielectrical spectroscopy method. We have investigated dielectric anisotropy values of the doped liquid crystals. The dielectrical relaxation mechanism of the doped liquid crystals was analyzed by Cole-Cole curves. The perpendicular and parallel components of the electrical conductivity of the doped liquid crystals were investigated as a dependence of frequency.The recently obtained scientific results were discussed using phenomenologic and theoretical models.Key Words: Liquid crystals, Smectic Textures, Optical Transmission, Optical Absorption, Phase Transitions, Heterophase Region, Dielectric properties.YILDIZ TECHNICAL UNIVERSITYGRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES