Redox-stable and visible/near-infrared electrochromic aramids with main-chain triphenylamine and pendent 3,6-di-tert-butylcarbazole units

Abstract

A series of visible and near-infrared (NIR) electrochromic aramids with main-chain triphenylamine and pendent 3,6-bis(tert-butyl)carbazole units were prepared from the phosphorylation polyamidation reaction of 4,4′-diamino-4′′-(3,6-di-tert-butylcarbazol-9-yl)triphenylamine with various aromatic dicarboxylic acids. These aramids were readily soluble in many polar solvents and could be solution cast into flexible and strong films. They showed useful levels of thermal stability associated with relatively high glass-transition temperatures (T_g) (295–321 °C) and high decomposition temperatures (no significant degradation occurred before 450 °C in nitrogen or air). In addition, the polymer films showed reversible electrochemical oxidation with enhanced NIR contrast, fast switching time, and anodic green/blue electrochromic behaviors.