Size-dependent catalytic effect of magnetite nanoparticles in the synthesis of tunable magnetic polyaniline nanocomposites

Nanocomposites comprising magnetic nanoparticles (NPs) embedded in an organic conducting polymer are promising materials that may allow one to exploit synergic effects between the electrically and magnetically permeable components. Having already shown magnetite NPs can be conveniently used as a catalyst for oxidative polymerization of aniline dimer resulting final composite how modulate coercivity composites, we now turn investigate size affects properties composite. Magnetite diameter 2.3, 10, 27 nm turned out effective catalysts with cheap oxidants such H2O2 O2. Yield data show rate-determining step occurs on NP surface. Extensive characterization shows well-dispersed no significant morphological change. The static composites widely different, e.g., blocking temperature shifts from 290 K 54 10 NPs, while 2.3 virtually unblocked down 5 K. dynamic electromagnetic behavior studied up microwave range only energy absorptions associated ferromagnetic resonance, at frequencies around 1 GHz.