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This paper presents an overview of the preparation, characterization, and potential application of thermochromic polymers. The term thermochromic describes materials which vary their color, color intensity, or transparency in response to temperature changes. Thermochromic effects have been observed in different types of polymer systems such as pure polymers, cross‐linked polymeric networks, polymer blends, and gels, whereby the origin of the thermochromic effect can be multifarious. The color can appear owing to absorption or owing to the physical effect of materials on light. The latter is called physical color and includes scattering and diffraction of light. Research in the field of thermochromic polymers has led to the discovery of novel effects producing thermochromism as well as to the development of thermochromic polymers with improved material properties. Moreover, rational design and optimization with a view to specific applications has started. Selected examples of the different classes of thermochromic polymers are presented and their characteristic material properties and potential applications are pointed out.

Until now, all thermochromic materials have contained at least one toxic or carcinogenic component which is a major shortcoming for their application especially in medical or food technology products. This paper describes the development of the first non-toxic and non-carcinogenic thermochromic polymer material. The material consists of the biopolymer poly(lactic acid) (PLA), a natural dye of the anthocyanidine class, a gallate derivative and a fatty acid. The origin of the observed thermochromic effect is a conformational change of the polymer backbone which reversibly triggers the formation of polymerdye complexes. Accordingly thermochromism represents an immanent property of the novel polymer material. The presented results establish a novel mechanism to realize the visualization of temperature changes in a way detectable by the human eye without any kind of auxiliary and provide a new approach for the development of thermochromic materials.

Mesogenic Chiral Dopants With Unusual High Helical Twisting PowerMesogenic chiral esters of 1-phenyl-1,2-ethandiol, l-cyclohexyl-l,2-ethanediol, 1,2-diphenyl-1,2-ethanediol, l,l'-bi-2-naphthol, 1-phenylethanol, 1-phenyl-2,2,2-trifluorethanol and l-(9-anthryl)-2,2,2-trifluorethanol were synthesized. The temperature dependence of the molecular twisting power was determined in the nematic wide range mixture RO-TN 404. All compounds show good solubility and unusual high values of the Einleitung