Steep electro-optical response of nematic liquid crystalline molecules induced by addition of polymeric chains

The steepness increases with a decrease in the ratio of elastic constants of the bend to the splay mode, K₃/K₁ The elastic constants of nematic directors are affected by the geometrical shape of a liquid crystalline molecule and a short range ordering for the alignment of liquid crystalline molecules. The magnitude of K₃/K₁ and the reorientational steepness of the nematic director were evaluated by an electric capacitance measurement of the (side chaintype liquid crystalline polymer (PS6EC)/low molecular weight liquid crystal (E7)) composite system cell. It became apparent from X-ray diffraction studies that the smectic-like short range ordering increases with increasing the fraction of PS6EC even in the nematic state of the composite system. Furthermore. a remarkably steep electro-optical response was successfully achieved.