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First example of a non-toxic thermochromic polymer material - based on a novel mechanism

: Seeboth, A.; Lötzsch, D.; Ruhmann, R.


Journal of materials chemistry. C, Materials for optical and electronic devices 1 (2013), Nr.16, S.2811-2816
ISSN: 2050-7526
ISSN: 2050-7534
Fraunhofer IAP ()

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.