In-situ synthesis and magnetic properties of polystyrene/polypyrrole nanocomposite materials with uniformly dispersed ir
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In-situ synthesis and magnetic properties of polystyrene/polypyrrole nanocomposite materials with uniformly dispersed iron nanoparticles H. Srikanth1, P. Poddar1, J. L. Wilson1, K. Mohomed2 and J. P. Harmon2 1 Materials Physics Laboratory, Department of Physics, University of South Florida, Tampa, FL 2 Department of Chemistry, University of South Florida, Tampa, FL ABSTRACT Magnetic nanoparticles embedded in polymer matrices have excellent potential for electromagnetic device applications like EMI noise reduction. We have synthesized polystyrene (PS) and polypyrrole (PPy) composites by controllably dispersing bare and PS-coated Fe nanoparticles. These nanocomposites were processed as spin-coated thin films as well as in bulk form. The processing conditions were optimized to achieve good uniform dispersion of the nanoparticles in the polymer matrix. SEM scans revealed clustering of nanoparticles which was particularly evident at the surface in the conducting polymer nanocomposites. Magnetic hysteresis loop measurements indicate large coercivities associated with the clusters and surface oxidation of the Fe particles. Overall, the excellent dispersion coupled with reasonable control over magnetic properties achieved in our experiments is promising for electromagnetic applications of these materials. INTRODUCTION Polymers have traditionally been considered as excellent host matrices for composite materials. Several advanced polymer composites have been synthesized with a wide variety of inclusions like metals, semiconductors, carbon nanotubes and magnetic nanoparticles [1, 2]. Many attractive properties of polymers like non-corrosiveness, light weight, mechanical strength and dielectric tunability can be utilized along with novel magnetic and optical properties of nanoparticles to make multifunctional materials. Inclusion of ferromagnetic or superparamagnetic nanoparticles in polymers is especially important as magnetic nanoparticles have shown promise in various potential applications like spin-polarized devices, carriers for drug delivery, magnetic recording media, high-frequency applications etc [3, 4, 5]. However, for most of these highly specialized applications, there is a practical need to disperse the nanoparticles in non-magnetic media that can be easily processed. Polymer materials are very well suited for this purpose. The effect of polymer permittivity on electromagnetic absorption in the microwave frequency range for polymer composites containing magnetic particles is another topic of recent interest [5]. The advantages of these materials in electromagnetic interference (EMI) reduction are due to desirable properties like frequency agility, light weight and non-corrosive nature. The magnetic particles in conducting polymer matrix are well suited for this purpose as effective magnetic shielding and increased resistance to eddy current losses are possible. In addition, combination of conducting and nonconducting polymers provides dielectric tunability. These characteristics make polymers viable and
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