Planer-Smoluchowski Soft Matter Workshop

Emergent Phenomena and Functional Materials

Julius Planer and discovery of thermotropic liquid crystal

In 1861, Prof. Julius Planer, at that time a professor at Lviv University, published a note which for the first time detailed the quintessential liquid crystalline features. He synthesized cholesteryl chloride, a material that is broadly known nowadays to form a liquid crystalline phase of cholesteric type upon cooling from the isotropic phase. Almost one and half century ago, Planer observed an unusual optical property: in a certain temperature range, the molten material exhibited a violet color in reflected light and yellow-green color in the transmitted light. The feature is typical of the cholesteric liquid crystal with helicoidal arrangement of molecule, having a submicron pitch that leads to the so-called “selective light reflection".

The note by Planer, originally published in German is now available in English

Also there is a note by Lisetski who reports experimental data on differential scanning calorimetry of the cholesteryl chloride and the spectra of selective light reflection that demonstrate that the optical feature observed by Planer is indeed caused by the cholesteric liquid crystalline phase of cholesteryl chloride.