Module 3: Liquid Crystals and Nanomaterials

Praveen P. Singh and Vishal Srivastava

Volume 4 | Issue 2 | Pages 32-36

Abstract

Liquid crystals were first accidently discovered in 1888 by Friedrich Reinitzer, a botanical physiologist who was working in the Institute of Plant Physiology at the University of Prague. Reinitzer was conducting experiments on a cholesterol-based substance (cholesteryl benzoate) and trying to determine the correct formula and molecular weight of cholesterol. When he tried to
precisely determine the melting point, which is an important indicator of the purity of a substance, he was struck by the fact that this substance seemed to have two melting points. He found a first melting point at 145.5 °C, where the solid crystal melted into a cloudy liquid. This ‘cloudy intermediate’ existed up to 178.5 °C where the cloudiness suddenly disappeared, giving way to a clear transparent liquid. At first, Reinitzer thought that this might be a sign of impurities in the material, but further purification did not show any changes in this behaviour. He concluded that the material had two melting points, but asked his colleague Otto Lehmann, a German physicist who was an expert in crystal optics, for help in understanding this unexpected behaviour. They isolated and analysed the ‘cloudy intermediate’ and reported seeing crystallites. Lehmann then conducted a systematic study of cholesteryl benzoate and other solids that displayed the double melting behaviour.

Keywords

Liquid crystals, Application of liquid crystals, Concepts of nanomaterials, Applications of nanomaterials

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