Facile preparation of electrochromic poly(amine–imide) films from diimide compounds with terminal triphenylamino groups via electrochemical oxidative coupling reactions

Two diamide compounds TPABP-DA and TPASO2-DA and two diimide compounds TPA6F-DI and TPASO2-DI with triphenylamine (TPA) end groups were synthesized from the condensation reactions of 4-aminotriphenylamine with respective aromatic dicarboxylic acids and tetracarboxylic dianhydrides. The diimide compounds can be electropolymerized into poly(amine–imide) films on the electrode surface in an electrolyte solution via the coupling reactions between the TPA radical cations. In contrast, electro-oxidation of the diamide analogs produced stable TPA radical cations that did not undergo electropolymerization reactions. The electrogenerated films of TPA6F-DI and TPASO2-DI showed a reversible oxidation redox couple with a half-wave potential (E1/2) of 0.96 V on their cyclic voltammograms. They exhibited stable electrochromic properties, with coloration change from a colorless neutral state to orange as a radical cation and blue when fully oxidized.