Electrooptical Properties of Main-Chain Mesogenic Polymers in Nematic State and Dilute Solutions

Electrooptical and dielectric properties of two aromatic polyesters with hexaethyleneglycol spacers (as well as their low molecular weight structural analogues) were studied in dilute solutions and in nematic state using the methods of flow birefringence, equilibrium electric birefringence, and orientational elastic deformations in electric fields. It was shown that the macromolecules under investigation orientated in the electric field according to the small-scale mechanism, and the Kerr constant K values are in good agreement with the dipole structure of their molecules. The sign of dielectric anisotropy Δϵ for the polymer nematics under investigation coincides with the sign of K in dilute solutions. The values of Δϵ for polymer nematics are close to the same characteristics for their low molecular weight structural analogues. The comparative analysis of the data obtained for these polymers in dilute solutions and in the nematic state is carried out.