ORIENTATIONAL ELASTISITY OF 4,4′-BIS-[ω-(4-CYANOBIPHENYL-4′-YLOXY)ALKYLOXY] BIPHENYLS NEMATICS

Abstract

Using the method of threshold Frederick's transitions in magnetic field were determined the values of splay orientational elastic constants K₁₁ of the nematic trimers 4,4′-bis-[ω-(4-cyanobiphenyl-4′-yloxy)alkyloxy]biphenyls with the number n of CH₂ groups in their spacers from 3 to 10. The dramatic odd-even effect in the dependence-of K₁₁ versus n for trimers was evaluated. This effect is mainly due to the oscillations of the degree of intermolecular orientational order in the series of the compounds under investigation. Using the values of K₁₁ the values of the dielectric anisotropy Δε of nematic trimers were calculated. The data obtained for trimers were compared with the same characteristics for dimers (4,4′-bis-cyanobiphenyloxyalkanes).

Key Words:

• nematics
• trimers
• orientational elasticity