Electric Field Effects in the Nematic and Smectic Phases of P-N-Nonyloxybenzoic Acid

Abstract

Samples of p-n-nonyloxybenzoic acid have shown a positive conductivity anisotropy in the nematic phase immediately after heating from the solid, but after a number of hours the anisot-ropy changed to negative. A possible explanation for this change is the formation of clusters of molecules by polymerization. The clusters could be linear polymers involving hydrogen bonds. A study of the temperature dependence of the conductivity anisotropy indicated that other mechanisms are involved such as the formation of cybotactic groups involving dimers. Molecular alignment due to ionic conductivity is discussed in both the nematic and smectic phases. The dielectric anisotropy which is positive in the nematic phase decreases with decreasing temperature and reverses sign as the material enters the smectic phase.