Research on Modification of Fe3O4 Magnetic Nanoparticles with Two Silane Coupling Agents

As a novel functional nanomaterial, Fe3O4 magnetic nanoparticles (MNPs) modified by different surfactants have attracted and are attracting worldwide interest. In this research, we introduced two different silane coupling agents to modify Fe3O4 MNPs instead of a single surfactant to achieve complete coating and functionalization. The modification mechanism was also explained. Techniques such as TEM, XRD, FT-IR, TG-DSC, and VSM were applied to characterize the obtained modified Fe3O4 sample. From these techniques, the following information is obtained: The characteristic bands of TEOS and KH-792 were present in the FT-IR spectra and in the XPS plots of modified Fe3O4 MNPs, demonstrating that the silane coupling agents were present in the sample obtained after the modification. The TG analysis of the modified sample showed complete decomposition at 228°C. The mass ratio of the sample obtained before and after the modification was close to 29:65. The XRD patterns show that the modified Fe3O4 MNPs possessed an identical reverse spinel crystal structure as an unmodified Fe3O4 sample. The modification decreased the saturation magnetization of Fe3O4 MNPs from 70.04 emu/g to 57.41 emu/g and the coating did not change the superparamagnetism of Fe3O4 MNPs.