Dielectric behavior in the nematic and isotropic phases of a strongly polar-weakly polar binary system

Abstract

We have performed measurements of the dielectric constant in the isotropic liquid and anisotropic liquid crystalline (nematic) phases of a binary system, in which one component has molecules with a strongly polar longitudinal group, and the other has a weakly polar transverse group. The transition between the two phases, being weakly first order, exhibits pretransitional effects signifying the appearance of the nematic-like regions in the isotropic phase. Unlike a typical polar liquid, the liquid phase of the strongly polar component of the binary mixture exhibits a convex shaped anomaly in its dielectric constant on approaching the nematic phase. We comment on the effect of the weakly polar component on the magnitude of this anomaly, as well as the nonlinear variation of the dielectric anisotropy. © 2012 American Institute of Physics.