Synthesis of electromagnetic functionalized barium ferrite nanoparticles embedded in polypyrrole.

With flaky BaFe12O19 nanoparticles (BF NPs, 10-20 nm in thickness) as polymerization seeds, electromagnetic functionalized and microstructured quasi-spherical PPY/BF (PPY: polypyrrole) organic-inorganic composites were prepared by a conventional in situ chemical oxidative polymerization. X-ray diffraction and Fourier transform infrared analyses interpreted that there was no obvious chemical interaction between BF NPs and PPY in the composites but that BF NPs only served as the nucleation sites for the polymerization of pyrrole. As compared to pure BF NPs, PPY/BF composites showed distinct increases in electrical conductivities and decreases in magnetization and thus improved the matched characteristic impedance of the free space, leading to a substantial enhancement of reflection loss at 2-18 GHz. For the first time, multi-layered and single-layered films formed at different places on the reaction flask were studied by scanning electron microscopy and energy dispersive X-ray analysis, indicating that the films composed of quasi-spherical microstructures can be very different in morphology but surprisingly contain no BF NPs.