Preparation of well-defined blackberry-like polypyrrole/fly ash composite microspheres and their electrical conductivity and magnetic properties

Composites consisting of conducting polypyrrole (PPy) and fly ash (FA) or amino-functionalized fly ash (A-FA) were prepared by the in situ chemical oxidative polymerization method, respectively. The surface functionalization of fly ash (FA) with amino groups was found to play an important role in the formation of the well-defined blackberry morphology. The scanning electron microscopy (SEM) analysis showed that the well-defined blackberry-like morphology of the polypyrrole/amino-functionalized fly ash (PPy/A-FA) composites with size range of 0.3-5 μm and the surface of the composites became smoother with more A-FA charged in the in situ chemical oxidative polymerization. X-ray diffraction (XRD) analysis of the PPy/A-FA composites showed the similar patterns as FA, which revealed that the crystal structure of FA was well-maintained after the surface functionalization and the in situ chemical oxidative polymerization. Thermogravimetric analysis (TGA) showed that the thermal stability of PPy/A-FA composites was enhanced and this could be attributed to the retardation effect of amine-functionalized fly ashes as barriers for the degradation of polypyrrole. The composites possess high electrical conductivity at room temperature, weak temperature dependence of the conductivity and good magnetic properties.