In this work, C@Fe3O4 magnetic microspheres were designed and prepared by a novel strategy, and the microwave absorption properties of the materials were investigated. Four kinds of monodisperse P(MAA/St) microspheres with different carboxyl content were synthesized via facile dispersion polymerization. The Fe3O4 nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@Fe3O4 microspheres. Using P(MAA/St)@Fe3O4 as the precursors, after vacuum carbonization, C@Fe3O4 were obtained. It was observed that the carboxyl content on the microspheres' surface increased with the increasing of MAA, which made the magnetic content and maximum specific saturation magnetization of P(MAA/St)@Fe3O4 and C@Fe3O4 increase. The obtained four kinds of C@Fe3O4 microspheres had a particle size range of 4-6 μm. The microwave absorption properties indicated that the magnetic content made a difference to the microwave absorption properties of C@Fe3O4 magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@Fe3O4 microspheres exhibited excellent microwave absorption properties. The maximum reflection loss could reach -45.6 dB at 12.8 GHz with 3 mm in thickness. The effective bandwidth was 5.9 GHz with RL < -10 dB. Therefore, C@Fe3O4 microspheres were lightweight and efficient microwave absorption materials.
Keywords: core/shell structure; dispersion polymerization; magnetic microspheres; microwave absorption; solvothermal method.