Electrolyte effects on the nematic–isotropic phase transition in lyotropic liquid crystals

Abstract

A phenomenological approach to the description of the electrolyte effect on the nematic–isotropic phase transition in lyotropic liquid crystals is proposed. The influence of the electrolyte is discussed by varying the coupling between the concentration variables and the orientational order parameter. The analysis shows that the discontinuity in the first order nematic–isotropic phase transition as measured by increases as a function of the weight fraction of the electrolyte. Here T NI is the first order nematic–isotropic phase transition temperature and is the extrapolated supercooling limit. The electrolyte dependence of the Cotton–Mouton coefficient and the non‐linear dielectric effect in the isotropic phase above the nematic–isotropic phase transition are calculated. The theoretical predictions are found to be in good agreement with experimental results.