Enhanced Study of Magnetic Properties of Polyvinyl Alcohol-Coated Superparamagnetic Iron Oxide Nanoparticles Below Blocking Temperatures

Superparamagnetic iron oxide nanoparticles (SPIONs) coated with the synthetic hydrophilic biocompatible polymer polyvinyl alcohol were synthesized using the aqueous method. Static and dynamic magnetization processes were investigated for surface-modified SPIONs by analyzing the magnetization study at constant and varying magnetic fields. The magnetization on the applied magnetic field (M–H) and the magnetization dependent on temperature (M–T) were investigated. The temperature dependence of the complex susceptibility of SPIONs was investigated by measuring the in-phase (natural) and out-of-phase (imaginary) components of the susceptibility value at a frequency of 10 Hz and a very low magnetizing field. The XRD study shows diffraction peaks consistent with the magnetite (Fe₃O₄) phase of SPIONPs. FTIR, DSC, and TGA studies confirm the functional groups and stability of the coated nanoparticles. The magnetizing field cycle study at various constant temperatures (10, 100, and 300 K) shows the high magnetization value of polyvinyl alcohol-coated SPIONs with superparamagnetic states at and above 300 K. The effect of interparticle interaction on blocking temperature has been interpreted from FC/ZFC curves drawn at different DC magnetizing field values by varying temperature between 10 and 300 K.