Dielectric spectroscopy of Polymer Stabilised Ferroelectric Liquid Crystals

Dielectric measurements were carried out in the frequency range from 20 Hz to 500 kHz on Polymer Stabilised Ferroelectric Liquid Crystals (PSFLCs). Polymerisation in the Smectic A* (Sm A*) and the Smectic C* (Sm C*) phase at equal polymer concentration results in a dielectric strength which is nearly twice the value in the latter case. An increase of the polymer concentration results in a decrease of the dielectric strength and an increase in relaxation frequency. The textural morphology and transmission intensity due to the residual birefringence of the polymer network in the isotropic phase, revealed a correlation between the interactions of the liquid crystal molecules with the polymer network. Results for polymerizing in the tilted Sm C* phase with a large bias field are also reported which show that the structure of the phase in which the system was polymerised affects the dielectric properties. The observed differences in dielectric behaviour can be explained by the polymer network morphology formed due to the interplay of phase and temperature on the stabilised ferroelectric liquid crystal materials.