Synthesis and characterization of highly conductive poly(indole-4-aminoquinaldine) copolymer

Conductive polymers with good conductivity and large surface area are used as N-precursor materials for N-doped carbon-based catalysts and increase the catalytic activity of the electrode. Therefore, synthesis of the novel highly conductive polymer is an essential issue. This study reports that the synthesis of a novel copolymer is called poly(indole-4-aminoquinaldine) successfully achieved both chemically and electrochemically. The effect of scan rate, scan number, monomer concentration, and solvent on the polymerization process was investigated, and hereby the optimum synthesis conditions for the copolymer were determined. Under optimum conditions, the polyindole was also synthesized electrochemically and properties of polyindole compared to poly(indole-4-aminoquinaldine). The electrochemical characterization was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrical conductivity of the poly(indole-4-aminoquinaldine) and polyindole was measured using a four-point probe technique as 6 S/cm and 1 × 10 –2 S/cm, respectively. Additionally, bandgap of copolymer and polyindole was found to be 3.10 and 3.18 eV, respectively. The structural, thermal, and morphological analysis of poly(indole-4-aminoquinaldine) and polyindole were carried out with UV–Vis Spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), elemental mapping, scan electron microscopy (SEM), and energy-dispersive X-ray analyzer (EDX) techniques. The novel copolymer synthesized in this study has high thermal stability and high electrochemical activity as well as high conductivity.