Wrinkled Fe3O4@C magnetic composite microspheres: Regulation of magnetic content and their microwave absorbing performance

In this work, we develop a novel synthetic strategy for wrinkled magnetic composite microspheres (Fe3O4@C). Firstly, hydrophobic oleic acid modified Fe3O4 (OA-Fe3O4) nanoparticles acted as the magnetic component are prepared by synchronous modification coprecipitation method. The macromolecular emulsifier with initiating activity is obtained by means of soap-free emulsion polymerization under the presence of 1,1-diphenylethylene (DPE). Then, interfacial polymerization is employed to synthesis Fe3O4@polymethylglycidyl ester/divinylbenzene composite microspheres (Fe3O4@PGMA/DVB). Fe3O4@C composite microspheres are obtained by vacuum carbonization of the microspheres. The effect of magnetic content on the microwave absorbing properties of Fe3O4@C composite microspheres is explored. The results show that Fe3O4@C composite microspheres exhibit the excellent application performance at the Fe3O4 content of 0.15 g. The reflection loss can reach -53.7 dB at only thickness of 1.7 mm. The Maximum effective absorption bandwidth is up to 5.26 GHz with a thickness of 1.9 mm. The microwave attenuation mechanism of Fe3O4@C composite microspheres is revealed. The excellent absorbing performance is attributed to the enhanced interfacial polarization ability, the surface wrinkled structure and the good synergy between dielectric and magnetic losses. This work provides an effective strategy for the design and preparation of new magnetic composite materials. (C) 2021 Elsevier Inc. All rights reserved.