History of Liquid Crystals

Abstract

The history of our field of interest is more clearly discernible when time periods are chosen which are covered by characteristic summarizing papers. Such papers can serve as the landmarks when a rather complex development is to be described briefly. So I shall report on the following periods: First period, was from the middle of the 19th century until 1908, comprising the discovery of liquid crystals, and work of predominantly descriptive character. Monographs, covering this period, are those of Lehmann ⁽¹⁾ (1904), Schenck ⁽²⁾ 1905, and Vorländer ⁽³⁾ (1908). The originals of all the older monographs are presented and held available for inspection. Second period, was from 1908 to 1922. This is the time of the first theoretical work and the foundation of systematology of liquid crystals. We must name E. Bose,⁽⁴⁾ M. Born,⁽⁵⁾ F. Stumpf⁽⁶⁾ (1918), G. Friedel⁽⁷⁾ (1922), and again D. Vorländer⁽⁸⁾ (1924) and O. Lehmann⁽⁹⁾ (1922). Third period, was from 1922 to 1933. This was perhaps the most fruitful period before the climax in the sixties. We note the development of quantitative theory and the investigation of the effects of outer forces and fields on liquid crystals. In 1929 a monograph was published by Oseen,⁽¹⁰⁾ “Liquid crystals, facts and theories”. The work of Ornstein, Kast, and Zocher will be dealt with later. Further chemical work was done predominantly at Halle (Vorländer), physical experimental work at Utrecht (Ornstein), at Leningrad (Fréedericks, later Zwetkoff) and in Poland (Jeåewsky). As a summary, a written discussion has been organized by P. P. Ewald in the Z. für Kristallographie 1930/31.⁽¹¹⁾ In 1933 the Faraday Society Meeting at London under Sir William Bragg took place.⁽¹²⁾ Fourth period, was from 1933 to 1945. This period brought new experimental work and some extension of basic theories, the foundation of later work. The Bunsen Discussion Meeting⁽¹³⁾ in 1938 was the last one before the war. Severe interruption and even complete collapse of international communication continued until the end of the war. The last work, comprehensive with respect to chemistry and morphology of liquid crystals was written in 1941 by Weygand.⁽¹⁴⁾ During the last period, beginning soon after 1945, we observe a strong revival which lasts until today. The activity in the sixties and seventies is beyond the scope of this historical review. In view of this fact, my review should be closed with the year 1945, and it will be biassed with respect to the early works.