Copolymerization of o-phenylenediamine and 3-Amino-5-methylthio-1H-1,2,4-triazole for tuned optoelectronic properties and its antioxidant studies

•Copolymerization of o-phenylenediamine and 3-Amino-5-methylthio-1H-1,2,4-triazole.•Tuned band gap and optoelectronic properties.•Enhanced solubility and processability.•Useful in designing optoelectronic devices.•Also a potential candidate for biomedical application. The functionalization of conjugated polymers via copolymerization is one of the most pliable methods adopted to enhance their photophysical and optical properties. The current work accounts for the first-time copolymerization of o-phenylenediamine (OPD) with 3-Amino-5-methylthio-1H-1,2,4-triazole (AMTT) in a 1:1 molar ratio, using potassium dichromate (K2Cr2O7) as an oxidant and surfactant sodium dodecyl sulfate (SDS) as a soft template. Spectral, thermal, morphological, and optical studies through Fourier transform infrared spectroscopy, UV–Vis spectroscopy and TGA confirmed the copolymerization of poly(OPD-co-AMTT). The analysis of FTIR spectra showed the presence of benzenoid and quinonoid moiety in almost equal proportion. UV–Vis spectroscopy revealed high oscillator strength for the synthesized copolymer. The study of fluorescence spectra revealed that the quantum yield was dependent on the monomer composition in the copolymer. XRD and TEM studies revealed structural modifications in the morphology of the polymers on copolymerization while thermal studies suggested graft copolymerization. Antioxidant studies revealed significant antioxidant activity of tailored copolymer against DPPH free radical and hydrogen peroxide.