Novel Polyamides with 5H-Dibenzo[b,f]azepin-5-yl-Substituted Triphenylamine: Synthesis and Visible-NIR Electrochromic Properties

In this study, a new diamine monomer, namely 4,4′-diamino-4”-(5H-dibenzo[b,f ]azepin5-yl)triphenylamine, was prepared and polymerized with four kinds of dicarboxylic acids via direct polycondensation reaction resulting in a novel series of soluble and electroactive polyamides (PAs). The tough thin films of all PAs could be solution-cast onto an indium-tin oxide (ITO)-coated glass substrate owing to the good solubility in polar organic solvents. Two pairs of obvious redox peaks for these films were observed in cyclic voltammetry (CV) with low onset potentials (Eonset) of 0.37–0.42 V accompanying with remarkable reversible color changes between light yellow and dark blue. A new absorption peak at around 915 nm emerged in near infrared (NIR) spectra; the increasing potential indicated that PAs could be used as a NIR electrochromic material. Moreover, the PAs showed high coloration efficiency (CE; η) in the range of 190–259 cm2 C−1.