Electro-optical properties of nematic lyotropic chromonic liquid crystals

• Electro-optical experimental apparatus based on TN liquid crystal cells is set up. • Electro-optical properties of nematic LCLCs are systematically measured. • Effects of slat and alkali on electro-optical properties of nematic LCLCs are studied. • Viscoelastic theory of nematic TLCs is proved to be applicable on nematic LCLCs. The electro-optical properties of liquid crystals play an important role in liquid crystal displays. Lyotropic liquid chromonic crystals are attracting the interest of researchers because of its extending application in areas of chemistry, medicine, and biology. An experimental apparatus is constructed based on nematic lyotropic chromonic liquid crystal sunset yellow filled in the twisted nematic liquid crystal cell to obtain two primary parameters of the electro-optical properties, the threshold voltage and relaxation time. The threshold voltage and relaxation time of nematic lyotropic chromonic liquid crystals decrease with the increase of temperature or the decrease of concentration. The concentration of neutral ionic dopants like sodium chloride and magnesium sulfate is positively correlated with the threshold voltage and relaxation time of nematic lyotropic chromonic liquid crystals, while the concentration of alkaline ionic dopants like sodium hydroxide exhibits a negative correlation. The changes of the electro-optical properties with respect to the temperature, solute concentration, and dopant concentration are analyzed based on the alteration of the molecular self-assembly behaviors of lyotropic chromonic liquid crystals. In addition, the viscoelastic theory of nematic thermotropic liquid crystals is proved to be also applicable on nematic lyotropic chromonic liquid crystals for the first time.