Influence of physicochemical interactions of capping agent on magnetic properties of magnetite nanoparticles

• Organic capped magnetite nanoparticles have been prepared by polyol method.
• The crystal structure and morphological analysis were studied by XRD, FESEM.
• Ethylene diamine (EDA) capped nanoparticles exhibit non saturation behavior.
• Mercaptopropionic acid (MPA) capped nanoparticles approaching the saturation state.
• Sulfur atom present in the MPA is chemically bonded with surface iron atom.

The properties of nanoparticles can be significantly altered by surface modification. In this present work the effect of surface inorganic–organic interactions on magnetic properties of magnetite nanoparticles have been investigated. Hence the mercaptopropionic acid (MPA) and ethylene diamine (EDA) capped magnetite nanoparticles have been prepared by polyol method. The magnetic study signifies that all the samples prepared by this method possess superparamagnetic behavior. The as-prepared, calcinated and EDA capped nanoparticles exhibit non saturation behavior, the MPA capped sample approach the saturation state and exhibit high value of magnetization whereas its calcinated sample shows complete saturation. The XRD results reveal that all the particles have nearly similar grain size so it is believed that the significant differences in magnetic properties are caused by the different interactions between the surface iron atoms and organic molecules. The XPS analysis indicates that sulfur atoms present in the MPA are chemically bonded with the surface iron atoms on the other hand, the EDA is physically adsorbed on iron oxide nanoparticles. Herein, we analyze and propose the possible interactions that could occur between the surface iron atoms and capping agent thereby influencing the magnetic properties of the nanoparticles.

The part of the MPA capping agent is chemically attached on the surface of iron atom through sulfur atom and part of them are attached via carboxylate group.Figure optionsDownload as PowerPoint slide