Siloxane-PEO-PPO Hybrid Materials Containing Superparamagnetic Iron Oxide Nanoparticles: Effect of Particle Surface...

This study explores the development and characterization of hybrid siloxane-polyether nanocomposites incorporating superparamagnetic iron oxide nanoparticles for potential applications requiring magnetic hyperthermia. The effect of the hydrophilic or hydrophobic surface functionalization of the nanoparticles on the structural features, magnetic properties, and hyperthermia performance of a siloxane-poly-(ethylene oxide) (PEO)-poly-(propylene oxide) (PPO) hybrid matrix has been investigated. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements revealed the successful synthesis of both the expected superparamagnetic iron oxide phases and the hybrid material, without compromising the structural integrity of the hybrid matrix. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM/EDS) showed aggregated iron oxide nanoparticles in the matrix forming microsized clusters. In contrast, small-angle X-ray scattering (SAXS) revealed the presence of well-dispersed iron oxide nanoparticles between the clusters, in agreement with particle-matrix interactions detected by FTIR and XRD. Magnetic characterization using a vibrating sample magnetometer (VSM) revealed that hybrids loaded with hydrophobic nanoparticles display a lower superparamagnetic behavior, and hyperthermia tests showed a reduced performance inside the hybrid matrix compared to hydrophilic nanoparticles. This reduction is due to the effective loss of particle coating when the nanoparticles are inserted into the hybrid matrix and a lower amount of organic coating (as detected by thermogravimetric analysis (TGA)), leading to a decrease in the magnetic moment and increased nanoparticle aggregation. These results confirm the importance of adequate control of nanoparticle surface chemistry for future optimization of hyperthermia properties of these promising flexible and biocompatible hybrid materials for innovative magnetic systems.