Dielectric Properties of Some Side Chain Liquid Crystalline Polymers

Abstract

Abstract An experimental setup to determine the anisotropic dielectric constants for liquid crystalline side chain polymers as function of the temperature and the frequency in the range between 100 Hz and 10 MHz is described. From the anisotropic dielectric data some more specific informations can be obtained comparing with the results obtained from unoriented samples. ‐ The anisotropic dielectric properties of two liquid crystalline side chain polymers containing the same polyacrylic main chain and slightly modified side chains are described in the glassy, nematic as well as in the isotropic state as function of temperature and frequency. For these compounds, three different relaxation processes are described. A process was found with the main component in ϵ ∥ due to the relaxation of the mesogenic side chain around the main chain back bone. A broad relaxation process, near above the glass temperature, with the main component in ϵ ⟂ is interpreted as due to diffusive motion of different dipoles. Another broad relaxation process occurs in the glassy state, containing parallel and perpendicular dipole components of the mesogenic ester group. In the isotropic state, the relaxation process is dominated by the parallel relaxation in the nematic state.