Air-stable Fe and Co crystalline nanocomposite particles prepared by a single-step swelling of metal precursors within polystyrene microspheres of narrow size distribution

Polystyrene template microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2- methoxyethanol. These template particles, dispersed in an aqueous solution, have been used to entrap Fe-3( CO)(12) and Co-2( CO)(8) complexes, using a single- step swelling process of methylene chloride and benzene emulsion droplets containing these complexes, within the particles. The e. ect of the swelling solvents ( methylene chloride and benzene) on the size and size distribution of the swollen template particles was elucidated. Air- stable Fe and Co nanocomposite particles have been prepared by thermal decomposition of the Fe-3( CO)(12) and Co-2( CO)(8) swollen template particles at 600 degrees C in an inert atmosphere. These nanocomposite particles have a core- shell structure, where a thin coating of metal oxide and carbon protects the core crystalline metal ( Fe and Co) from oxidation. The characterization of the various microspheres and the air- stable Fe and Co nanocomposite particles was accomplished by light microscopy, TEM, SEM, XRD, XPS, elemental analysis, and magnetic measurements.