Magnetite nanoparticles-catalyzed synthesis of conductive poly(p-aminodiphenylamine)

Para-aminodiphenylamine (p-ADPA) was successfully polymerized by simple, economical and environmentally improved procedure. Magnetite nanoparticles (Fe3O4 NPs) were found to successfully catalyze the oxidation of p-ADPA in the presence of hydrogen peroxide (H2O2), an eco-friendly and clean oxidant, with a very small amount of ammonium peroxydisulfate (APS) as an initiator. In this manner, the amount of by-products occurring during the reaction is drastically reduced. The oxidation of p-ADPA proceeded also in the absence of Fe3O4 NPs, but far more slowly than the catalyzed process. The influence of the mass ratio Fe3O4NPs/p-ADPA on the properties of products was systematically studied by different characterization techniques. Spectroscopic measurements (UV-Vis-NIR, FTIR, Raman, EPR) indicate that the polymerization products are polyaniline emeraldine salt-like polymers and their measured electrical conductivity is one of the highest values reported in the literature for p-ADPA oligomerization/polymerization products (1.8∙10-2 S cm-1). X-ray powder diffraction (XRPD) measurements revealed highly crystalline structure of Poly(p-ADPA) samples synthesized with Fe3O4 NPs, while scanning electron microscopy (SEM) showed layered and prismatic-shaped particles as prevailing in their morphology.