Effects of nonmesomorphic substituted benzonitriles on the dielectric properties of cyanobiphenyl liquid crystals

The effects of the cyano-substituted aromatic nonmesomorphic additives N-(3,4-dicyanophenyl)-4′-nonyloxybenzamide (I), 3,4-dicyanophenyl-4′-nonyloxybenzoate (II), 3,4-dicyanophenyl-3′,4′,5′-tris-(4″-undecyloxyphenylbenzoate)benzoate (III), and 4-(6-hydroxyhexyloxy)benzonitrile (IV) on the dielectric properties of 4-hexyloxy-4′-cyanobiphenyl and a liquid-crystal mixture E3 were studied. Dielectric anisotropy, birefringence, and orientational ordering were studied to show that monocyano derivative IV most strongly increased the dielectric anisotropy of mesomorphic compositions because of its effective incorporation into the liquid crystal matrix.