Impact of varying magnetite nanoparticle concentrations on the structural, electrical, and magnetic properties of polyaniline-based magnetic nanocomposites

We report the synthesis of polyaniline/magnetite nanocomposites (PMNCs) via in situ chemical oxidation polymerization of aniline with magnetite nanoparticles (MNPs) at 5, 12, and 25 wt%. The objective was to evaluate how the MNPs’ proportion affects the electrical, magnetic, and structural properties, which were investigated using XRD, EDXRF, TEM, EIS, ESR spectroscopy, Mössbauer spectroscopy, and VSM. EDXRF confirmed the formation of MNPs, while XRD revealed the crystalline nature of MNPs and the semicrystalline structure of PANI, with a decrease crystallinity index as the MNPs percentage increased. TEM showed PANI encapsulating MNPs with average diameters of 9.7 ± 2, 9.9 ± 2, and 13.1 ± 3 nm for PMNC25, PMNC12, and PMNC5, respectively. Conductivity values of PANI, PMNC25, PMNC12 and PMNC5 were 7.96 ×10⁻⁴, 1.38 ×10⁻⁴, 2.19 ×10⁻⁴ and 2.31 ×10⁻⁴ S/cm, respectively. ESR indicated cationic radicals responsible for conductivity. Saturation magnetization (Ms) for MNPs, PMNC25, PMNC12 and PMNC5 were 93.4, 24.6, 11.8 and 5.6 emu/g, respectively, with superparamagnetic behavior observed. Our findings show that incorporating MNPs into the PANI matrix modulates electrical conductivity and magnetic properties while maintaining the nanocomposite’s structure, highlighting the multifunctional potential of these composites.