A stimuli-responsive viologen-containing polymer for use in electrochromic devices and amine-detecting paper

Viologens exhibit excellent color responses to external stimuli owing to their desirable redox properties. They have been widely studied in electrochromic and photoluminescent materials. Generally, polymeric materials have better processing properties and longer service life than small organic molecules. Herein, a viologen-containing polyurethane was synthesized and used to prepare an electrochromic device and a paper-based amine detector. The obtained electrochromic device displayed an excellent electrochromic behavior when subjected to an external voltage as low as 1.0 V. Moreover, the designed paper-based amine detector exhibits a highly sensitive color-change response when exposed to liquid amine solutions (down to 1 ppm concentration) or gaseous ammonia. The results of this study demonstrated that the developed viologen-containing polyurethane exhibits excellent electrochromic performance and the designed amine-detecting paper chips are an excellent tool for amine detection.