Nanoferrites as catalysts and fillers for polyaniline composites preparation

Materials displaying both electrical and magnetic propperties are drawing much interest as the combine the advantages typical of inorganic materials (mechanical strength, electrical and magnetic features, thermal stability) with those of organic compounds (flexibility, ductility, and processing). Among them, intrinsically conducting polymers (ICPs) containing magnetic nanoparticles (NPs) can find various potential applications in electromagnetic interference shielding, electrochromic devices and non-linear optical systems. Polyaniline (PANI) is one of the most investigated ICPs thaks to its extraordinary electrical characteristics, reversibly switching from an insulator to a conducting material by facile deprotonation/protonation processes. PANI can exist in different forms: leucoemeraldine (totally reduced form), emeraldine (half-oxidized forma), pernigraniline (totally oxidized form) and other intermediate structures. PANI/NPs composites are typically prepared by multi-step approaches involving NPs synthesis followed by aniline polymerization. The inorganic particles can be embedded during the polymerization process or in a subsequent step. Inspired by our experience in the field of catalysis, as well as in the preparation of conducting polymers by innovative eco-friendly protocols, we recently reported a new method to produce electrical and magnetic polyaniline nanocomposites (PANI/Fe3O4 and PANI/CoFe2O4), whereby the magnetic nanoparticles play the double role of catalyst and magnetic filler. In order to extend this study to PANI nanocomposites with different nanoferrites, we investigated the catalytic properties of nanosized MFe2O4 (M= Mn, Ni, Cu, Zn, Mg) in the N-(4-aminophenyl)aniline oxidatice polymerization to achieve PANI/MFe2O4 nanocomposites displaying notable electrical and magnetic properties.