Superparamagnetic polymer nanocomposites with uniform Fe < inf > 3 < /inf > O < inf > 4 < /inf > nanoparticle dispersions

Abstract

Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential for applications such as electromagnetic interference shielding, magneto-optical storage, biomedical sensing, flexible electronics, etc. Control over the dispersion of the nanoparticle phase embedded in a polymer matrix is critical and often challenging. To achieve excellent dispersion, competition between polymer-polymer and polymer-particle interactions have to be balanced to avoid clustering of particles in polymer nanocomposites. We report the first deposition of magnetic nanocomposite poly(methyl methacrylate)/polypyrrole bilayers from solution using spin-coating. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Using a combination of dissolving the polymer and mixing fatty acid surfactant coated Fe3O4 nanoparticles, we have demonstrated the formation of nanocomposites with uniform nanoparticle dispersion. Cross-sectional scanning electron microscopy, transmission electron microscopy, and magnetic measurements confirm the excellent dispersion and super-paramagnetic response. Low-frequency impedance measurements on these bilayers are also presented and analyzed. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.