Compósitos superparamagnéticos à base de magnetita e complexo interpolieletrolítico

Abstract

Magnetite nanoparticles are one of the most studied magnetic materials due their extremely low toxicity, superparagnetic behavior at room temperature and low costs, with potential for wide use in medical application as drug release, hyperthermia and magnetic separation. The functionalization of magnetite nanoparticles has been extremely promising in recent decades, since it causes dimensional and chemical modifications on the surface of the particles, taking them to new applications. Chitosan are widely used to improve biocompatibility of magnetic particles, in order to yield particle systems more adequate for application in biomedicine. Chitosan has amino groups in its macromolecular structure, which in acid condition become protonated, resulting in positive NH 3   groups so that it can be used as coating for particles as well as in the preparation of polymer network composites. In this work, magnetic composites were obtained by chemical precipitation between chitosan and poly (sodium 4- styrenessulfonate) in presence of magnetite nanoparticles, which was studied for (SO3 - /NH3 + ) molar ratios of 1.43 and 0.7. in order to compare, Interpolyeletrolyte complexes were prepared with the same proportion and without the presence of magnetite nanoparticles. Composite composition and magnetite microstructure were investigated by termogravimetric analysis (TGA), Fourier transformed Infrared spectroscopy (FTIR), X-ray powder Diffraction (DRX), Transmission electron microscopy (TEM) and zeta potential (  ). Magnetic characterization was performance by Field cooled (FC) and zero Field Cooled (ZFC) magnetization experiments, as well as magnetic hysteresis measured in different temperature. TGA and FTIR confirmed the presence of Chitosan, poly (sodium 4-styrenessulfonate) and magnetite in all composites, furthermore, the thermal event verified in TGA results for magnetic composites agree with IPEC structure. DRX and TEM showed that magnetite had no change their structural features during the preparation of composites, being approximately 12 nm for all samples. Composite surface charge was altered according to (SO3 - /NH3 + ) molar ratio, being positive for the composite with ratio 1.43 and negative for ratio 0.7 ( ). The magnetic characterization shows that both magnetic composites are superparamagnetic in room temperature (25°C).