Broadening of the Nematic Temperature Range by a Non-Mesogenic Solute in a Nematic Liquid Crystal

Abstract

The general rule that addition of a non-mesogenic solute causes a sharp decrease in the nematic-isotropic transition temperature (T_{N→ I}) of a nematic solvent is not obeyed when the solute and solvent can enter into a donor-acceptor interaction. Addition of 4-aminobiphenyl to the nematic liquid crystal 4-cyano-4′-pentylbiphenyl (nematic range ∼ 25–35°) leads to an increase in T_{N→ I} and a decrease in the crystal-nematic transition temperature. The maximum nematic range (21–38°) is achieved at ∼ 7 mole % solute.