New Nematic Liquid Crystals: Influence of Rigid Cored, Alkenyl Side-Chains and Polarity on Material and Display Properties

Abstract

Abstract From the design of non-polar molecular structures exhibiting different rigid cores and isolated C=C double bonds in different side-chain positions and from investigations into the static dielectric birefringence, viscous, and all three elastic constants k 1, k 2, k 3, new, negative dielectric anisotropic nenatic liqueid crystals result, namely apolar alkenyls, which are shown to cover a wide range of materail porpertie, including large twist constants k 2. The combination of double bonds in 4-position, with rigid cores comprising heterocyclic rings is shown to lead to exceptionally low elastic rations k 3/k 1 ∼ 0.4 with simultaeoulsy low optical anisotropies and low roatational viscosities γ1. Moreover, laterally substituted alkenyls are shown to exhibit large negative dielectric anisotropies rendering them applicable for low viscous, positive contrasat guest-host mixtures with high order parameters 0.72≤ S ≤ 0.78. The stability of the new nematics comprising isolated double bonds is shown to be ...