Mitsuyoshi Ichihashi

Chiral smectic C liquid crystals having an electronegative substituent ortho to the chiral tail group - a study of a factor determining the magnitude of spontaneous polarization

Abstract Chiral smectic C compounds having an ester group in the central core, an optically active tail group (alkoxy or alkoxycarbonyl), and an electronegative substituent (halogen or cyano) ortho to the chiral tail were synthesized. The effect of the ortho substitution on the characteristics, especially on spontaneous polarization (Ps), was examined. When the chiral tail is a 1-methylheptyloxy group the lateral substituent increases Ps relative to the unsubstituted analogue. In the case of 1-methylheptyloxycarbonyl tail group, however, the lateral substituent decreases Ps relative to the unsubstituted. These effects of lateral substituents are explained in terms of chemical structure of a single molecule, i. e., by taking statistical weight of conformers and the associated electric dipole moments into account.

Smectic Layer Switching by an Electric Field in Ferroelectric Liquid Crystal Cells

Switching between two different smectic layer structures, chevron and bookshelf geometries, was observed for the first time in ferroelectric liquid crystal cells. In the absence of an electric field, a chevron layer structure is formed, as in a usual smectic C* phase. An electric field induces layer switching to a bookshelf geometry with a sharp DC threshold. Accompanying the layer switching, the projection of the director onto glass plates changes from the smectic layer normal to one of the uniform states when an electric field is applied. This optical change is equivalent to what is recognized as tristable switching.