Lehmann, Otto

Weiterhin mochten sich die Autoren auch bei den Mitarbeitern der Fachabteilung II.3 der Bundesanstalt fur Materialforschung und -prii-fung (BAM) bedanken. Hier waren Herr Dr. D. Eckhardt, Herr Dr. Th. Lehmann und Herr Dr. J Otto zu nennen. 

Over a century ago, Professor Otto Lehmann of the University of Karlsruhe - who is acknowledged as the pioneer of liquid crystal technology - disagreed with the scientific establishment about the existence of the liquid crystalline state of aggregation. Lehmann turned to Merck. He asked the company to supply him (and others) with liquid crystalline compounds so that he could clarify what no amount of theoretical debate could resolve. This was Merck s first foray into the LC business - although there was no actual business at this stage. Nevertheless, it was already well known that Merck supplied products of the highest purity, which allowed results to be replicated accurately. 

Koch MC, Steinmeyer K, Lorenz C, Ricker K, Wolf F, Otto M, Zoll B, Lehmann-Horn F, Grzeschik KH, Jentsch TJ. The skeletal muscle chloride channel in dominant and recessive human myotonia. Science 1992 257 797-800. 

The term liquid crystal was first applied to compounds that, unlike most compounds that melt in a single step at a definite temperature, show one or more well-defined phases between the solid and the true liquid. Otto Lehmann in 1888 was contacted by Friedrich Reinitzer who had observed that crystalline cholesteryl benzoate, on heating, seemed to have two melting points.At 145.5° C a cloudy liquid forms that, on further heating, changes sharply to a clear liquid at 178.5° C. On cooling the reverse order of phases was found. The turbid liquid is doubly refracting, like the anisotropic crystals described in Chapter 5, hence the... 

We wish to thank Dr. Darrell D. Nicholas, Mr. Roy D. Adams and Ms. Susan Mateer of the Institute of Wood Research at Michigan Technological University for their work in conducting the mixed hardwood flakeboard experimental program. We also wish to thank Dr. Michael 0. Hunt of Purdue University and Dr. William F. Lehmann of Weyerhaeuser Corporation for their help in the red oak flake-board work and Mr. Otto G. Udvardy of Borden Chemical for the aspen waferboard study. Finally, we would like to thank Dr. Ronald Taylor of Mobay Chemical Corporation for his considerable advice and help with the multiple correlation analysis. 

The discovery of liquid crystals by humans is due to the Austrian botanist Friedrich Reinitzer [14] what he observed in 1888 were cholesteric MLCs (see Section 41.3.1). Some people did not believe Reinitzer that such strange structures are possible. However, a German scientist named Otto Lehmann asked Reinitzer for some samples, conducted similar experiments, and reported virtually identical results a year later [15]. Given the popirlar disbelief, Lehmaim s resirlts were not exactly trivial. Lehmaim also coined the name liquid crystals —over objections of Reinitzer, who said the name is wrong and constitutes a contradiction. As you can easily imagine, there were cen-tennnial celebrations in Austria in 1988 and in Germany in 1989. 

Fig. 1.2 Photos of Friedrich Reinitzer (/ ) and Otto Lehmann (right)...

In 1975 P.G. de Gennes recognized that the interplay between liquid crystalline order and the macromolecular network stmcture generates new physical properties that also resemble those of biological systems and muscles [3]. In the following years Otto Lehmann s early ideas were actually demonstrated with liquid crystalline elastomers although at that time the basic concepts of macromolecular chemistry were still unknown. 

Phase winding in cholesterics was first observed by Otto Lehmann, the physicist father of liquid crystals, and is known as the Lehmann effect. Brand and Plainer [3] were the first to account for the Lehmann effect with a straightforward symmetry argument that can be used to extract a Lehmann coefficient [2]. 

Liquid crystals are materials that exhibit order intermediate between that of a solid crystal and that of a regular liquid [1]. As a consequence, liquid crystals present imique characteristics. For example, a liquid crystal may flow like a liquid, but its molecules are oriented along a characteristic length scale. The first report [2] of a liquid crystal material comes from Friedrich Reinitzer in 1888. Reinitzer observed that cholesteryl benzoate melted at 145.5 °C into a cloudy liquid that persisted until the temperature reached 178.5 °C. At this latter temperature the cloudiness disappeared. Reinitzer and his colleague Otto Lehmann determined that the cloudy liquid was a new state of matter. The properties of cholesteryl benzoate led Lehmann to coin the term liquid crystal in 1889 [3]. 

The first scientific description of liquid crystals was provided by the Austrian botanist Friedrich Reinitzer. This was in 1888, hence in 1988 we had celebrations of 100 years of discovery of liquid crystals. We also had celebrations in 1989, because in 1889 the German scientist Otto Lehmann coined the name liquid crystals . Lehmann confirmed the experimental results of Reinitzer, which was important, since some people did not believe Reinitzer. However, Reinitzer was not exactly grateful he maintained that the name liquid crystals is wrong and constitutes a contradiction. 

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