Synthesis and characterization of trifluoromethylated poly(ether–imidazole–imide)s based on unsymmetrical diamine bearing carbazole and imidazole chromophores in ionic liquids: Study of electrochemical properties by using nanocomposite electrode

A novel aromatic trifluoromethylated diamine containing various functional groups was synthesized and characterized by using different spectroscopic techniques. The diamine was polymerized with various dianhydrides in a green media of ionic liquid (IL) without using NMP–pyridine–acetic anhydride. The poly(ether–imidazole–imide) (PEII)s were obtained in good yields (80–96%) with moderate viscosity (0.33–0.67 dL g−1) in a shorter reaction time (10 h vs. 36 h) in IL. The resulting polymers were fully characterized and their properties such as solubility, viscosity, crystallinity, thermal, photophysical, and electrochemical behavior were investigated. They were amorphous and showed excellent solubility even in common organic solvents, such as chloroform and m-cresol, with ability to form tough and flexible films. The films were colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range 304–337 nm and the wavelength of 80% transparency in the range 375–400 nm. Furthermore, they also possessed good thermal and thermo-oxidative stability with 10% weight loss temperatures (T10%) in the range 441–528 °C in N2 atmosphere and in the range 382–494 °C in air. The glass transition temperatures of all polyimides are in the range 204–302 °C.Their electrochemical behavior was also studied by using adsorptive stripping cyclic voltammetry and impedance spectroscopy on the multi-walled carbon nanotube-modified glassy carbon electrode.

Graphical abstractA series of novel thermally stable poly(ether–imidazole–imide)s bearing ether linkage, substituted imidazole, carbazole ring and bulky CF3 groups in the backbone was successfully prepared by polycondensation reaction between a new unsymmetrical diamine and commercially available dianhydrides via a two-stage method including poly(amic acid) formation and chemical imidization and a one stage method in imidazolium based ionic liquids without using NMP–pyridine–acetic anhydride.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel aromatic trifluoromethylated diamine with various functional groups was synthesized. ► The poly(ether–imidazole–imide) (PEII)s were synthesized in good yields in ionic liquid. ► The polymers were soluble in common organic solvents and their films exhibited high optical transparency. ► These polymers showed good thermo-oxidative stability up to 494 °C in air and Tgs at 302 °C.