Liquid Crystals: Between Order and Disorder

Abstract

In 1888, the botanist Friedrich Reinitzer [9.5] was studying cholesterol in plants. He had the idea of observing a cholesterol benzoate crystal through the microscope as it underwent melting. At 145.5°C, the crystal became cloudy but fluid. It then transformed into a transparent liquid, very like water, at 178.5°C. The natural inclination of any physicist would have been to doubt the purity of the sample. Indeed, this had been the conclusion of those scientists who had previously made the same observation. Reinitzer, however, trusted in the quality of his compound. He therefore introduced the idea that melting could take place in two stages, and in this way opened up a new area of research: the study of liquid crystals, intermediate states between liquids and solids.