Rotational Viscosity of a Bent-Core Nematic Liquid Crystal

Abstract

We report the detailed measurements of the rotational viscosity (γ1) of a bent-core nematic liquid crystal exhibiting positive dielectric anisotropy by measuring the decay time of the optical phase retardation of the sample. In the nematic phase, γ1≃0.25 Pa s (e.g., at T/TNI≃0.92, where TNI is nematic to isotropic phase transition temperature.), which is only slightly larger than the values known for several conventional calamitic nematic liquid crystals. γ1 starts to increase rapidly below a reduced temperature T/TNI≃0.9 showing the effect of short-range smectic fluctuations. The temperature dependence of γ1 far from the nematic to smectic-C transition temperature is fitted well with the Osipov–Terentjev theory.