Micellar shape anisotropy and elastic constants in discotic lyotropic liquid crystals

TL;DR

This paper models the elastic constants of discotic lyotropic nematic liquid crystals based on micellar shape anisotropy, linking theoretical predictions with experimental data near the nematic-isotropic transition.

Contribution

It introduces a pseudo-molecular approach to relate micellar shape anisotropy with elastic constants and their temperature dependence in lyotropic liquid crystals.

Findings

Theoretical predictions match experimental measurements of elastic constant ratios.

Temperature dependence of elastic constants is linked to micellar shape anisotropy.

Phenomenological determination of elastic constants near phase transition.

Abstract

The elastic constants of a discotic lyotropic nematic liquid crystal are calculated by means of a pseudo-molecular approach as functions of the micellar shape anisotropy. By assuming that the temperature dependence of the ratio of the elastic constants comes from the temperature dependence of the micellar shape anisotropy, the theoretical predictions are connected with experimental measurements for the ratio $K_{33}/K_{11}$. This procedure permits to determine, in a phenomenological way, the temperature dependence for the ratio of elastic constants and for the micellar shape anisotropy near the nematic-isotropic transition in agreement with the experimental data.