ANISOTROPY OF RADIOTRACER DIFFUSION IN SOME NEMATIC LIQUID-CRYSTALS

The radiotracer impurity diffusion coefficients D11 = D22 and D33 4-n-panty-4-cyanobiphenyl (5CB), 4-n-octy 1-4-cyanobipheny1 (8CB), 4-n-pentyloxy-4-cyanobipheny1 (50CB), and 4-n-octyloxy-4-cyanobiphenyl (80CB) have been determined over their nematic phase. An electromagnet was used for the particles orientation and diffusion of impurity which was water solution of natrium pertechnate (NaTcO4), traced with Tc — 99m was investigated. Using literature data for the temperature dependence of the order parameter S, given for 5CB and 8CB, a relation between the anisotropy of diffusion coefficients and order parameter S is discussed. The linear dependence obtained between the diffusion coefficients and the order parameter S is analogous to the equations obtained by author for the anisotropy of other transport properties, i.e. viscosity and heat conduction coefficients, for the same liquid crystals. © 1992, Taylor & Francis Group, LLC. All rights reserved.