Synthesis and investigation of benzidine − aniline and benzidine − o-anisidine copolymers with PANi like structure

• Conductive copolymers synthesized from benzidine, aniline, and o-anisidine. • Optimized copolymerization enhanced solubility and conductivity. • Copolymers exhibit excellent thermal stability. • Structural characterization confirmed quinone-diimine units in PANi-like chains. • Synthesis avoided typical side reactions of benzidine in organic media. • Doped copolymers showed conductivity comparable to PANi and polyoAns. Copolymerization of benzidine with aniline and o-anisidine was performed via oxidative polymerization using ammonium persulfate in an organic medium. The composition of the resulting copolymers was analyzed by proton magnetic resonance (PMR) spectroscopy for initial benzidine-to-o-anisidine molar ratios of 1:0.5, 1:1, and 1:2. The study demonstrates that the physicochemical properties of the copolymers—including ultraviolet–visible (UV–Vis) absorption characteristics, solubility, thermal stability, electrical conductivity, and morphology—can be tuned by adjusting the ratio of quinonediimine to substituted structural units within the polyaniline (PANi)-like chains. The copolymers exhibited high thermal stability, retaining 66–72 % of their weight up to 600 °C. When doped with hydrochloric acid (HCl), their electrical conductivity was comparable to that of the parent homopolymers, polyaniline and polyanisidine. These findings suggest the potential of structural modulation to enhance the functional performance of PANi-based copolymers for advanced materials applications.