ORIENTATIONAL ORDER AND ELASTIC DEFORMATIONS IN NEMATIC TEXTURES 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 optica l anisotropy of nematics (Delta n=n(e)-n(o)) and threshold electric po tentials V-o of deformations of their monodomain planar texture were d etermined at different temperatures. In both dependences of Delta n an d I/V-o on n strong odd-even effect is manifested. However, the charac ters of alternations observed in them differ greatly. These difference s are due to the fact that the value and sign of I/V-o depend not only on the intermolecular (nematic) orientational order but is determined to a much greater extent by intramolecular order which depends on the polar and polarizing architecture of the molecule.