Mechanism of electro-optical switching hysteresis for (polymer/liquid crystal) composite films

The relationship between the hysteresis characteristics of electro-optical switching and the compatibility at the polymer–low molecular weight liquid crystal (LC) interface was studied for the (polymer/LC) composite film prepared by a solvent cast method. The interfacial phase-mixing behavior between polymer and LC components was evaluated on the basis of the dielectric relaxation on an interfacial polarization at the polymer–LC interface and FT-IR ATR spectra. When the polymer was not compatible with LC even in its isotropic state, no hysteresis on the applied voltage-light transmittance relationship was detected for the electro-optical switching. It is suggested that the phase-mixing at the polymer–LC interface induced upon the application of an electric field is a possible mechanism affecting the electro-optical switching hysteresis.