Rotational viscosity of nematic lyotropic chromonic liquid crystals

Abstract

Lyotropic chromonic liquid crystal has great application potential in the areas of the biology, medicine, and optics due to its biocompatibility, nontoxicity, biodegradability and birefringence. The rotating magnetic field method was used to measure the rotational viscosity of nematic Sunset Yellow, disodium cromoglycate and Sunset Yellow doping of magnesium sulfate, sodium chloride and sodium hydroxide at various temperatures and concentrations. The rotational viscosity of nematic lyotropic chromonic liquid crystals is positively correlated with the square of the average length of columnar aggregates, increasing with the increase of concentration, but decreasing exponentially as temperature increases. This paper established a universal empirical expression of the rotational viscosity of nematic lyotropic chromonic liquid crystals and presented that the largest relative deviation between theoretical calculation and experimental results is only 22.60%. The rotational viscosity of nematic lyotropic chromonic liquid crystals becomes intensive with the increasing of magnesium sulfate and sodium chloride concentrations, while it reduces with the increase of sodium hydroxide concentration. The “one-step method” is proposed here that one sample of nematic LCLCs at various temperatures can replace normal materials to evaluate the influences of the shape anisotropy of molecules or colloidal particles on the research target, such as physical property parameters, depletion interaction potentials, and so on. This method is based on the self-assembly ability difference of lyotropic chromonic liquid crystal molecules at various temperatures and has been proved to be reliable by comparison with the results obtained from many samples of nematic 5CB, CBP5, 5PCB, et al.