Visible and near-infrared electrochromic polymers with naphthyldiphenylamine redox chromophores

A novel diamide-diamine monomer, N , N’ -bis[4-(4-aminobenzamido)]- N , N’ -di(2-naphthyl)-1,4-phenylenediamine, was synthesized and polymerized with three aromatic tetracarboxylic dianhydrides to produce three new poly(amide-imide)s (PAIs), each featuring two redox-active triarylamino cores in its repeating unit. The resulting polymers exhibited excellent solubility in polar organic solvents and could be solution-cast into strong, flexible films with high thermal stability. Their cyclic voltammograms revealed two distinct and reversible redox processes within a potential range of 0 to 1.5 V. Upon oxidation, all the PAIs exhibited visible and near-infrared dual-band electrochromic behavior. The polymer films underwent a color change from a colorless neutral state to grass green at the first oxidation stage, and then further transformed to dark blue at the second stage. All the PAIs demonstrated high electrochemical and electrochromic stability during both the first and second redox processes.