Orientational Order and Elastic Deformations in Nematic Texturfs of bis-4-Cyanobiphenyloxyalkanes in an Electric Field

Using the method of orientational elastic deformations in an electric field we investigated the electrooptical properties of nematics of the bis-4-cyanobiphenyloxyalkanes series differing in the number n of CH2 groups in the oxymethylene chain of the molecule. The value of optical anisotropy of nematics (Δ n=ne - no) and threshold electric potentials Vo of deformations of their monodomain planar texture were determined at different temperatures. In both dependences of Δ n and I/Vo on n strong odd-even effect is manifested. However, the characters of alternations observed in them differ greatly. These differences are due to the fact that the value and sign of I/Vo depend not only on the intermolecular (nematic) orientational order but is determind to a much greater extent by intramolecular order which depends on the polar and polarizing architecture of the molecule.