Splay-bend elasticity and rotational viscosity of liquid crystal mixtures of rod-like and bent-core molecules

We report temperature dependent measurements of birefringence (Dn), splay (K11), bend (K33) elastic constants and rotational viscosity (g1) of mixtures of rod-like and bent-core molecules. K11 and Dn remain almost constant for all the mixtures whereas K33 is always lower than K11 and further decreases with increasing concentration of bent-core molecules in the mixtures. Apart from the large jump in Dn at the nematic-isotropic transition (NI) a significant jump in Dn at the nematic-smectic transition (NS) is also observed that increases with increasing mol% of the bent-core compound in the mixtures. Rotational viscosity increases by a factor of four when the concentration of the bent-core compound increased from 0 to 10 mol%. The results are discussed on the basis of their structural similarity and mutual alignment in the nematic phase.