Synthesis and characterization of soluble donor-acceptor type copolymers based on benzotriazole, quinoxaline and benzene units with multicolor electrochromism

Three soluble donor-acceptor (D-A) type copolymers employing benzene (B) as donor, 2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo [d][1,2,3]triazole (Z) and 2,3-bis((4-(2-octyldodecyl)oxy)phenyl)-quinoxaline (Q) as acceptors were synthesized through chemical polymerization. A variety of characterization methods such as cyclic voltammetry , UV–vis spectroscopy, colorimetry and thermogravimetric analysis were executed to detect the electrochromic properties of polymers. All the polymers displayed multicolor in the redox process with medium band gaps, and different molar ratio of B/Z/Q allowed them to cover diverse color changes, containing orange-red/brown-yellow/cyan/green (PBZQ-1), orange-red/yellow/light grass green (PBZQ-2), and red/black/grey-blue (PBZQ-3). The multichromism of the polymers involved RGB and black colors. Meanwhile, with the increase of Z unit ratio and the decrease of Q unit ratio, the polymer demonstrated the reduced onset oxidation potential and optical band gap, as well as the different kinetic parameters . Moreover, the three polymers exhibited good solubility, desirable thermal stability, relatively large optical contrast and high coloration efficiency. The above positive results implied that these copolymers were expected to be the credible candidates for the electrochromic devices with commercial values.