Effect of fluorine type liquid crystal on electro-optical switching hysteresis for (polymer/liquid crystal) composite films

Fluorine type low molecular weight liquid crystal(LC) dependence of the hysteresis of electrooptical switching and the phase-separated structure was investigated for the (polymer/LC) composite film cast from a uniform solution. It is confirmed from morphological observation by scanning electron microscopy (SEM) that the LC domain size of the composite film containing fluorine type LCs remarkably decreased. The interfacial phase-mixing behavior between polymer and LC components was evaluated by the time domain method based on the dielectric composite model of the (polymer/LC) composite film, the temperature dependence of the composite film and the atomic force microscopy (AFM). The hysteresis of electro-optical switching for the composite film was strongly dependent on the LC type. When the polymer and the LC were not compatible such as (Poly(methyl methacrylate)(PMMA)/fluorine type LC) composite system, the static hysteresis of the electro-optical switching for the composite film was not observed. It is found that the phase-mixing at the polymer-LC interface upon applying an a.c. electric field had great effect on the electro-optical switching hysteresis of the composite film.