Transmissive to black electrochromic aramids with high near-infrared and multicolor electrochromism based on electroactive tetraphenylbenzidine units

A series of near-infrared (NIR) electrochromic aromatic polyamides with tetraphenylbenzidine (TPB) units were prepared by phosphorylation polyamidation from a newly synthesized aromatic diamine monomer, N, N'-bis(4-aminophenyl)-N,N'-di(4-methoxyphenyl)-4,4'-biphenyldiamine, and various dicarboxylic acids. These polymers were highly soluble in many organic solvents and showed useful levels of thermal stability associated with high glass-transition temperatures and char yields. These anodically polymeric electrochromic materials showed reversible electrochemistry and electrochromism with high contrast ratio both in the visible range and NIR regions. Notably, copolymerization of TPB-based and TPPA-based aramids (TPPA: tetraphenyl-p-phenylenediamine) showed a good combination of the individual homopolymers in electrochemical and electrochromic properties, producing a transmissive-to-black electrochromic polymer with high NIR and multicolor electrochromism.