Superparamagnetic polymer nanocomposites with uniform Fe3O4 nanoparticle dispersions

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 superparamagnetic response. Low-frequency impedance measurements on these bilayers are also presented and analyzed.