Synthesis and Characterization of PMMA Coated Magnetite Nanocomposites by Emulsion Polymerization
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Synthesis and Characterization of PMMA Coated Magnetite Nanocomposites by Emulsion Polymerization Ming Zhang, and Charles J O'Connor Chemistry/AMRI, University of New Orleans, New Orleans, LA, 70148
Abstract In this paper, we report the synthesis and characterization of the poly-methyl methacrylate (PMMA) coated magnetite nanocomposite obtained from the emulsion polymerization method. In this approach, the magnetite particles were prepared separately with oleic acid as the capping ligands in nonaqueous solution and disperse in non-polar solvent. The micelle structure consisting water, oil phase and surfactant will contain the oleic acid stabilized magnetite particles inside and the polymerization process will only occur on the surface of the emulsion system. This method allows the individual magnetic particles encapsulated in the polymer matrix. The resulting nanocomposites were characterized by TEM, XRD and SQUID.
INTRODUCTION Nano-scale magnetic particles of uniform size are intensively drawing the attention because they exhibit the significantly enhanced chemical, optical, electrical, magnetic and catalytic properties. Especially, magnetite (Fe3O4) nanoparticles hold a great deal of promise for biomedical applications such as magnetic resonance imaging, biological separation and drug delivery.1-5 One of the most recent interests is the functionalizing the surface of magnetic nanoparticles for applications in biomedicine which require narrow size distribution or uniform monodispersed nanoparticles with desired chemical and biological surface functionalities. In such applications, the nanoparticles would benefit from having a shell structure to increase the mechanical stability, water solubility, and biocompatibility and prevent aggregation. Biocompatible polymer is proved to be one of the best coating materials due to its chemical stability and transparency6-9. Recently many research efforts have been devoted to the preparation of monodispersed superparamagnetic nanoparticles, where polymers have been used in their surface modification. Among the various synthetic strategy of polymer coating, there are three major experimental routes to make polymer coated magnetic nanoparticles. First route is so-called one-pot synthesis which polymer is used as capping ligands to bind to the magnetic particles directly during the particles formation process.10 The second route is based on the ligand exchange reaction between polymer and capping ligand on the surface of magnetic nanoparticles.11,12 Those two methods both use pre-made polymer for binding and attaching to the surface of magnetic particles. For the third experimental route the monomer is used as precursor and the polymerization process occurs on the surface of
the magnetic particles. Dr Yang and his coworkers reported that the Fe2O3@polystyrene core-shell structure nanoparticles can be obtained by atom transfer radical polymerization (ATRP) method.13 The key step of the synthesis is to apply the ligand exchange process with 2-bromo-2-methylpropionic
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