Novel Fe3O4/phthalonitrile alkyl-containing hybrid microspheres and their microwave absorption application in phthalonitrile composites

• A novel Fe3O4/organics microsphere was prepared by one-step solvent-thermal route.
• The hybrid microsphere exhibited uniform diameter and outstanding magnetism.
• The magnetic composite possessed excellent microwave absorbing properties.

To develop high performance electromagnetic absorbing composites, novel microwave absorbers and high performance polymer matrices are the essential issues which must to be taken into consideration. Herein, we reported novel Fe3O4/4-nonylphenoxy-1, 2-dinitrilbenzene (Fe3O4/NP-ph) hybrid microspheres and their microwave absorption applications in phthalonitrile composites was systematically investigated. Firstly, Fe3O4/NP-ph hybrid microspheres were prepared by one-step solvent-thermal route. Scanning electron microscope (SEM) observations indicated that Fe3O4/NP-ph hybrid microspheres with the size of 100±10 nm were self-aggregated, which was confirmed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) characterizations. Results of magnetic and electromagnetic properties indicated that Fe3O4/NP-ph hybrid microspheres possessed excellent magnetism (106.1 emu/g) and outstanding microwave absorption properties both in bandwidth and value. Based on this, Fe3O4/NP-ph hybrid microspheres reinforced phthalonitrile containing benzoxazine (BA-ph) composites were studied. The calculated reflection losses showed that the microwave absorption reached −37.1 dB at 10.1 GHz with a matching thickness of 5 mm. Besides, all of the magnetic composites demonstrated excellent thermal stability up to 420 °C in nitrogen. Meanwhile, the incorporation of Fe3O4/NP-ph hybrid microspheres and BA-ph matrix opened up a new route to develop magnetic composites as a promising candidate for microwave absorbing materials in high-temperature applications.