Controlling synthesis of Fe nanoparticles with polyethylene glycol

This study looks at the synthesis of Fe nanoparticles using a borohydride reduction of metal salts in the presence of carboxyl and methoxyl terminated polyethylene glycol (PEG). As the PEG concentration is varied, there is a corresponding increase in the Fe content of samples as determined by Mossbauer spectroscopy. Particle sizes are between 70 and 300 nm as indicated by transmission electron microscopy. As the polymer concentration is increased the overall saturation magnetization of the coated nanoparticles initially increases due to the increased iron content with a maximum of 70 emu/g for nanoparticles with the largest Fe content. The magnetization then begins to decrease as the polymer concentration begins to contribute to a significant volume fraction of the sample. All samples are magnetically soft with high remanence as indicated by SQUID magnetometry measurements.