Role of polyvinyl pyrrolidone as a capping agent in the synthesis of magnetite (Fe₃O₄) nanoparticles

Abstract

Uncapped magnetite (Fe₃O₄) and magnetite capped with polyvinyl pyrrolidone (PVP) (Fe₃O₄-PVP) have been synthesized by a rapid, cost effective aqueous precipitation method. The nanoparticles are characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and UV spectroscopy. The role of PVP as a capping agent in the synthesis of magnetite nanoparticles has been investigated. Thermal stability and surface charge of the nanoparticles have been characterized by thermogravimetric analysis, differential scanning calorimetry (DSC) and zeta potential measurements. Results suggest that PVP as a capping agent reduces the grain size, regularizes the shape, and increases the crystallinity of Fe₃O₄ nanoparticles. Thermal stability and surface charge of Fe₃O₄-PVP nanoparticles are also significantly higher as compared to the uncapped Fe₃O₄ nanoparticles. Magnetic characterization by vibrating sample magnetometry of both Fe₃O₄ and Fe₃O₄-PVP nanoparticles indicates the superparamagnetic behavior of the nanoparticles.