Microemulsion synthesis and electromagnetic wave absorption properties of monodispersed Fe3O4/polyaniline core–shell nanocomposites

Monodispersed Fe ₃O ₄ /PANI core–shell nanocomposites were synthesized by microemulsion polymerization. Before the polymerization of aniline, Fe ₃O ₄ nanoparticles were prepared by thermal decomposition of iron acetylacetonate using benzyl alcohol as the solvent and were surface-modified by oleic acid. Then aniline monomer was polymerized on the surface of Fe ₃O ₄ nanoparticles by microemulsion polymerization with sodium dodecyl benzene sulfonate as the surfactant and ammonium persulfate as the oxidant. Fourier transform infrared (FT-IR) spectra indicated that the oleic acid was chemisorbed on the surface of Fe ₃O ₄ nanoparticles. Transmission electron microscopy (TEM) analysis showed that the oleic acid modified Fe ₃O ₄ nanoparticles had a better dispersity with a diameter around 10 nm. The Fe ₃O ₄/PANI nanocomposites were monodisperse with Fe ₃O ₄ as the magnetic core and PANI as the conductive shell. The as-prepared Fe ₃O ₄/PANI nanocomposites showed a superparamagnetic behavior. The paraffin composites with 70 wt.% Fe ₃O ₄/PANI powders provided good electromagnetic wave absorption performance (RL < −20 dB) in the range of 10.01–16.98 GHz with absorber thicknesses of 3–4 mm. A minimum RL value of −25.40 dB was observed at 10.52 GHz with a thickness of 3 mm.