Synthesis and Electrochromic Properties of Aromatic Polyamides with Pendent Triphenylamine Units

Three series of electroactive polyamides are prepared, from 4‐(3,5‐diaminobenzamido)triphenylamine (4), 4‐(3,5‐diaminobenzamido)‐4′,4″‐di‐ tert ‐butyltriphenylamine ( t ‐Bu‐4), and 4‐(3,5‐diaminobenzamido)‐4′,4″‐dimethoxytriphenylamine (MeO‐4), respectively, with aromatic dicarboxylic acids via phosphorylation polyamidation reactions. The resulting polyamides are easily soluble in polar organic solvents and can be solution‐cast into flexible and strong films. They exhibit high thermal stability with glass transition temperatures ( T g ) in the range of 264–306 °C and 10% weight‐loss temperatures in excess of 470 °C. The polyamides derived from diamines t ‐Bu ‐ 4 and MeO‐4 exhibit reversible electrochemical oxidation, accompanied by strong color changes with high contrast ratio and electrochromic stability. The remarkable electrochromic behavior of the polymer film is clearly interpreted on the basis of spectro‐electrochemical studies. For the polyamides derived from diamine 4 , the triphenylamine radical cations formed during the oxidative process will dimerize to a tetraphenylbenzidine structure, leading to an additional oxidation state and color change.