Tunable negative dielectric properties of magnetic CoFe2O4/graphite-polypyrrole metacomposites

In this work, the CoFe2O4/graphite-polypyrrole (PPy) metacomposites with negative dielectric constant were prepared by the surface-initiated-polymerization method. The dielectric constant of CoFe2O4/graphite composites is positive, while the dielectric constant of CoFe2O4/graphite-PPy composites is negative. The regulation of the negative dielectric constant of CoFe2O4/graphite-PPy metacomposites was accomplished by changing the content of CoFe2O4/graphite. The negative dielectric constant of 10.0 wt% CoFe2O4/graphite-PPy metacomposites reaches −1.82 × 103 in the measured frequency range. The crystal structure, chemical structure, and microstructure of all the samples were analyzed by the XRD, FT-IR, Raman, and SEM systematically. All the characterizations indicate that the CoFe2O4/graphite-PPy metacomposites were successfully fabricated. Meanwhile, the magnetic properties of the samples were reported in this work. The remanence, coercivity, and saturation magnetization is 10.50 emu g−1, 0.314 T, and 25.34 emu g−1 for CoFe2O4/graphite-PPy metacomposites with a CoFe2O4/graphite loading of 40.0 wt%. This work provides the guideline for fabrication of polymer-based metacomposites with tunable negative dielectric constant. Graphical abstract: [Figure not available: see fulltext.]