Dependence of Helical Pitch on Composition in Mixtures of Nematic and cholesteric Liquid Crystals

The dependence of helical pitch on composition and its phase diagram in many nematiccholesteric mixtures was measured. It has been known about the nematic-cholesteric mixtures that the reciprocal pitch versus composition curve deviates considerably from a straight line. In this paper, the deviation is discussed in relation to the molecular structure of components and smectic thermal stability in the mixtures. It is concluded that a lateral intermolecular interaction plays an important role in the helical pitch of nematic-cholesteric mixtures.