Some Optical Properties of dispersed Cholesteric Liquid Crystals

Abstract

High iridescence has been achieved by the dispersion of cholesteric liquid crystals in polyurethane elastomers. A model based on Frank's disclination theory is proposed whereby the aggregate size and pitch determine a textural change from a spherulitic texture to an “aligned” plane texture as the size of the dispersed aggregate decreases. This is accomplished by the different free energy relationships of radial and surface defects in the dispersed state. Discussion of the model and experimental observations center on the morphological, chemical and physical parameters which determine high iridescence of dispersed cholesteric liquid crystals and hence the effect of these parameters on the topological role of defects in attaining high iridescence.