Novel triphenylamine-based polyamides: Efficient preparation via benzoxazine-isocyanide-chemistry at room temperature and electrochromic properties investigation

Abstract

A type of novel triphenylamine (TPA)-based diisocyanide derivative, 4-isocyano-N-(4-isocyanophenyl)-N-(4-methoxyphenyl)aniline (M1), was successfully synthesized via Hofmann treatment of its primary amine precursor (2). A series of polyamides (P1–P3), which containing TPA units in backbones, were successfully synthesized via efficient benzoxazine-isocyanide-chemistry (BIC) at room temperature by using M1 and bifunctional benzoxazines as starting monomers. Chemical structures of P1–P3 were verified by FT-IR, 1H NMR and gel permeation chromatography (GPC) analyses. Polymers’ films were prepared by solution coating (using DMSO as solvent), and electrochemical properties of P1–P3 were investigated by cyclic voltammetry (CV). P1–P3 exhibited single-step highly reversible oxidation process, reflecting their good electrochemical activity. Electrochromic properties of polymers were further analyzed by spectroelectrochemical techniques. New absorption bands at ~750 nm appeared in UV–vis spectra of P1–P3 when the applied voltage reached ~0.65 V, accompanied by the obvious visual color change (from colorless to blue-green). Response time and coloration efficiency of P1–P3 were also investigated here. The work carried out in this study proved that BIC can act as powerful tool to construct novel functional polyamides.