A simple aminoalkyl siloxane-mediated route to functional magnetic metal nanoparticles and magnetic nanocomposites

Abstract

Magnetic nanoparticles have emerged as an important class of functional nanostructures with applications in various fields of biology and medicine. We have developed a simple synthetic route for functional Co nanoparticles which further allows their direct integration into Co@SiO₂ microspheres, a synthesis that could be also applied to Fe nanoparticles. One advantage of the method described herein, compared to other methods for the synthesis of Co nanoparticles and Co@SiO₂ nanocomposites, is the direct decomposition of the dicobalt octacarbonyl precursor in the presence of a silane coupling agent, therefore allowing an easy and size-controlled synthesis of siloxane-functionalized nanoparticles and the further preparation of magnetic nanocomposites. As shown by infrared spectroscopy, nanoparticle formation proceeds via an initial homonuclear disproportionation reaction. We could further show that the size of the particles can be controlled by varying the reaction parameters. The size, structure, and magnetic properties of the particles were characterized by transmission electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, X-ray diffraction, atomic emission spectroscopy, and magnetic measurements.