Preparation and characterization of Fe₃O₄ nanoparticles coated with succinic anhydride-modified polypropylene glycol

The development of magnetic Fe₃O₄ nanoparticles with universal dispersibility in both polar and non-polar media remains a significant challenge for advanced ferrofluid applications. In this study, polypropylene glycol (PPG) was chemically modified via esterification with succinic anhydride to introduce terminal carboxyl groups, facilitating its robust anchoring onto Fe₃O₄ nanoparticles through a facile co-precipitation route. The resulting Fe₃O₄@mPPG nanoparticles maintained a spherical morphology with a primary core size of approximately 9.5 nm. FT-IR spectroscopy and TG-DSC analysis confirmed the successful grafting of the modified PPG (mPPG), with surfactant loadings of 4.2% (mPPG400) and 6.7% (mPPG1000). Magnetization measurements revealed that the particles retain high superparamagnetism (M _s > 63 emu g^-1), despite a slight reduction caused by the magnetic dilution effect of the coating layer. Zeta potential analysis demonstrated superior colloidal stability at pH < 4 and pH > 10, where absolute values exceeded 30 mV. This research provides a robust strategy for synthesizing "solvent-agnostic" magnetic nanomaterials, bridging the gap between polar and non-polar dispersion requirements.