BEHAVIOR OF THE ELECTROCLINIC EFFECT AND THE SOFT MODE ROTATIONAL VISCOSITY IN THE SMECTIC-A PHASE OF FERROELECTRIC LIQUID-CRYSTALLINE POLYMER MONOMER MIXTURES

Measurements of the electroclinic effect in the smectic A phase of a c hiral side-chain polyacrylate, of a low molecular mass liquid crystal with very similar structure and of mixtures between these two compound s are reported. The ratio of the induced tilt angle and the electric f ield strength is found to be independent of the concentration, whereas the coupling constant between induced tilt and induced polarization d ecreases with increasing amount of polymer. This behaviour of the elec troclinic effect implies a considerably lower tilt controlling suscept ibility coefficient for the chiral polyacrylate than for the low molec ular mass compound. The values of the soft mode rotational viscosity o f the polyacrylate, which are obtained from the electrooptical measure ments in combination with dielectric spectroscopy, are found to be thr ee orders of magnitude larger than for the monomer.