Polypyrrole-CoFe2O4 nanocomposites: Polymer influence on magnetic behavior and particle effects on polymer conduction

Composites of cobalt ferrite nanoparticles in a polypyrrole (PPy) matrix have been synthesized in acid media and characterized by X-ray diffraction studies, scanning and transmission electron microscopy observation, thermogravimetric analysis, conductivity, and infrared spectroscopy measurements. Two types of composites were prepared: one including dodecylbenzenesulphonic acid as a particle protector and another one without protection. The magnetic behavior was studied through DC magnetization measurements; hysteresis loops were observed, showing ferromagnetic behavior for particles and composites. Materials with particle protection showed magnetic parameters independent of the PPy/ferrite ratio; in the absence of protector, both the coercivity and remanence ratio decreased as the PPy/ferrite ratio increased. These results are attributed to conducting polymer effects on the ferrite particles, affecting the magnetic anisotropy. On the other hand, composites with low PPy/ferrite ratio showed positive magnetoresistance of up to 20% at room temperature, indicating an effect of the magnetic particles on polymer conduction. POLYM. COMPOS., 39:4617-4627, 2018. (c) 2017 Society of Plastics Engineers