Effect of Field Strength on Electrooptical Properties of Low-Molecular Weight and Polymer Liquid Crystals

The influence of a strong electric field on isotropic melts of 6-cyanobiphenyl and comb-shaped polyacrylate with side mesogenic groups was investigated. It was established that the electric field induces the isotropic—nematic phase transition in melts of these compounds. A relaxation process was discovered that destroys the nematic ordering induced in substances by electric fields. It was found that the relaxation time τ of the orientational order parameter is proportional to the square of electric field strength. For comb-shaped polymer liquid crystals, the time of transition from the nematic to the isotropic phase is several orders longer then that for low-molecular liquid crystal.