Triphenylamine-based redox-active aramids with 1-piperidinyl substituent as an auxiliary donor: Enhanced electrochemical stability and electrochromic performance

A new triphenylamine-based diamine monomer 4,4′-diamino-4″-(1-piperidinyl)triphenylamine was synthesized and polymerized with various aromatic dicarboxylic acids via the phosphorylation polyamidation technique leading to a series of redox-active aromatic polyamides (aramids). All the aramids exhibit good solubility in many organic solvents and can be solution-cast into flexible and strong films with high thermal stability. Cyclic voltammograms of the polymer films on the indium-tin oxide (ITO)-coated glass substrate exhibit a pair of well-defined and reversible oxidation waves with very low onset potentials of 0.27-0.35 V (vs. Ag/AgCl) in acetonitrile solution, with a strong color change from colorless neutral form to green and deep blue oxidized forms in the range of 0.75-1.20 V. The optical transmittance change (Δ%T) at 636 nm between the neutral state and the fully oxidized state is up to 83%.