Synthesis and Characterization of Ferromagnetic Polymer-Coated Cobalt Nanoparticles in Multi-Gram Quantities

Abstract

Ferromagnetic cobalt nanoparticles (CoNPs) are of interest due to their inherent dipolar properties which enable one-dimensional (1-D) nanoparticle self-assembly. As their magnetic properties change drastically with their size, the ability to selectively synthesize monodisperse metallic nanoparticles of varying diameters remains a crucial challenge. Although there have been extensive studies performed on various metallic nanoparticles yielding superparamagnetic materials (such as Fe3O4, Fe2O3, Co metals), research concerning the synthesis of ferromagnetic materials has only recently resurged within the last 20 years.In this work, methods for the synthesis of ferromagnetic cobalt nanoparticles on multi-gram scales were investigated. A one-pot synthetic method which produced up to 4 grams of cobalt nanoparticles per reaction was developed, and it was also found that this reaction had a direct correlation with particle size and reaction temperature, allowing for the large-scale synthesis of polystyrene-coated cobalt nanoparticles of pre-selected diameters.