Novel anodic electrochromic aromatic polyamides with multi-stage oxidative coloring based on N, N, N′, N′-tetraphenyl-p-phenylenediamine derivatives

A series of novel aromatic polyamides with pendent 4,4'-dimethoxy-substituted triphenylamine (TPA) units were prepared via the direct phosphorylation polycondensation from a new dicarboxylic acid monomer, N, N-bis(4-carboxyphenyl)-N', N'-di(4-methoxyphenyl)-1,4-phenylenediamine (4), and various aromatic diamines. These polyamides were amorphous with good solubility in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP) and N, N-dimethylacetamide (DMAc), and could be solution-cast into flexible polymer films. They had excellent levels of thermal stability associated with their relatively high glass-transition temperatures (233-308 degrees C). These polymers exhibited strong UV-vis absorption bands at 351-363 nm in NMP solution. Their photoluminescence spectra showed maximum bands around 450-504 nm. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the polyamide 6g prepared from the dicarboxylic acid monomer (4) with a structurally similar diamine monomer N, N-bis(4-aminophenyl)-N', N'-di(4-methoxyphenyl)-1,4-phenylenediamine (5g) exhibited four reversible oxidation redox couples in acetonitrile solution at E-onset = 0.35, E-1/2 = 0.64, 0.84, and 0.99 V, respectively. After over 3000 cyclic switches for green color, the films of polyamide 6g still showed excellent continuous cyclic stability of electrochromism.