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

• We prepared nano Fe3O4/PANI particles by microemulsion polymerization.
• The Fe3O4/PANI composites were monodispersed with core–shell structure.
• The Fe3O4/PANI provided good electromagnetic wave absorption performance.

Monodispersed Fe3O4/PANI core–shell nanocomposites were synthesized by microemulsion polymerization. Before the polymerization of aniline, Fe3O4 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 Fe3O4 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 Fe3O4 nanoparticles. Transmission electron microscopy (TEM) analysis showed that the oleic acid modified Fe3O4 nanoparticles had a better dispersity with a diameter around 10 nm. The Fe3O4/PANI nanocomposites were monodisperse with Fe3O4 as the magnetic core and PANI as the conductive shell. The as-prepared Fe3O4/PANI nanocomposites showed a superparamagnetic behavior. The paraffin composites with 70 wt.% Fe3O4/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.