Study of Smectic Layer Structure of Polymer-Stabilized Ferroelectric Liquid Crystal with Grayscale Memory

Infinitesimal liquid crystal domains useful for grayscale memory are induced in ferroelectric liquid crystal devices in which a small amount of polymer is oriented and dispersed in the nematic phase. The authors studied the effect of the dispersion state of the polymer on the structure of the smectic layer in order to identify the formation mechanism. X-ray diffraction measurements indicated that the inclination angle of the smectic layer of chevron structure is decreased significantly by reducing the size of the polymer aggregations in the fast photopolymerization-induced phase separation. Further, observations with a polarizing microscope indicate that the displacement angle of the smectic layer direction from the rubbing normal direction is also decreased by reducing the size of the polymer aggregations. These phenomena are caused by the attraction of the liquid crystal molecules to the polymer orientation direction by polymer penetrating into the liquid crystal. There is a strong possibility that this anchoring effect makes the threshold voltage for bistable switching fluctuate and induces the fine domain structure.