Characterization of Fe3O4 and Fe2O3 ferrogels prepared under uniform magnetic field

Abstract

ABSTRACTWe compare the characteristics of ferrogels prepared with and without the presence of a uniform magnetic field using Fe3O4 and Fe2O3 nanoparticles immobilized in hydrogels of N-isopropylacrylamide. The spatial distribution and agglomeration of the nanoparticles within the ferrogels were investigated using ultra small angle x-ray scattering (USAXS) and transmission electron microscopy (TEM). Hydrated ferrogels were also studied for magnetization using direct current superconducting quantum interference device (DC-SQUID). Volume size distribution resulting from USAXS data of the Fe3O4-ferrogel prepared under a uniform 225 G magnetic field showed a single broad peak appreciably different from that prepared without magnetic field with three distinct peaks. Volume size distributions resulting from USAXS data of the Fe2O3-ferrogel prepared with and without the presence of a uniform magnetic field both similarly show two peaks. Nanoparticle agglomeration was also determined by analyzing TEM images of ferrogel samples. DC-SQUID measurements of Fe3O4-ferrogel prepared in the presence of a uniform magnetic field showed 9% higher magnetization compared to the Fe3O4-ferrogel prepared without magnetic field. Similarly, DC-SQUID measurements of Fe2O3-ferrogel prepared in the presence of a uniform magnetic field showed 3% higher magnetization compared to the Fe2O3-ferrogel prepared without magnetic field. Thus, the presence of a uniform magnetic field during ferrogel polymerization can enabled the enhancement of the magnetoelastic property of the ferrogel.