Studies of the Temperature-Pitch Variations in Planar Cholesteric Layers and Surface Anchoring

摘要

Analysis of the temperature dependence of themeasured optical characteristics of planar oriented cholesteric(CLC) layers shows that just before the change of the number ofhalf-pitches within the layer thickness by one, the director directionat the surface essentially differs from the alignment direction andthe jump temperature is dependent on the direction of thetemperature change (cooling or heating). A theoretical descriptionof this hysteresis is presented on the basis of a continuum theory ofelasticity of CLC's that takes also account of the surface anchoring.Because the observed hysteresis and deviation angle are dependenton the molecular anchoring forces at the surface the correspondingmeasurements fitted to the developed theory are used to obtaininformation about the anchoring potential. The possible ways ofthe, model independent, anchoring potential reconstruction and thedifferent jump mechanisms are discussed.