Permittivity, Conductivity, Elasticity, and Viscosity Measurements in the Nematic Phase of a Bent-Core Liquid Crystal

We report on measurements of dielectric permittivity ε, electrical conductivity σ, elastic moduli k ii , and rotational viscosity γ for a bent-core nematic liquid crystal. The static permittivity anisotropy εa = ε∥ − ε⊥ is negative; at a given temperature in the interval 107−123 °C, ε∥ shows two relaxations falling in the frequency bands 20−200 kHz and 0.9−2 MHz; ε⊥ also shows a relaxation between 0.9 and 5 MHz. The conductivity anisotropy σa = σ∥ − σ⊥ is negative at low frequencies; it changes sign twice at frequencies f 1 and f 2 that increase with temperature, in the ranges 6.5−10 and 95−600 kHz, respectively. Surprisingly, the splay modulus k 11 is considerably greater than the bend modulus k 33 in the entire nematic range. Viscous relaxation is more complex than in calamitic systems involving at least a two-step process. The γ values are an order of magnitude greater compared to calamitics.