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. © 2017 Society of Plastics Engineers