Síntesis de un Material Magnético Tipo Core/Shell de Nanopartículas de Maghemita Recubiertas por una Estructura Mesoporosa Ordenada

NICOLÁS A. FELLENZ; IGNACIO PEREZ DE BERTI; SILVANA J. STEWART; SERGIO G. MARCHETTI; JOSÉ F. BENGOA

Puerto Iguazú

Congreso; 13 Congreso Internacional en Ciencia y Tecnología de Metalurgia y Materiales/SAM-CONAMET 2013; 2013

Sociedad Argentina de Materiales

A synthesis of a novel material composed by nanoparticles (NPs) of maghemite (γ-Fe2O3) functionalized with oleic acid, coated by an ordered mesoporous silica, is reported. The γ-Fe2O3 NPs were prepared following standard procedures in air atmosphere and using commercially available reagents. The average NPs diameter was 9 nm determined using Dynamic Ligth Scattering technique (DLS). The coating of the magnetic NPs was carried out at room temperature (RT) using teatraetilortosilicate (TEOS) as silica source and a cationic surfactant as mesoporous structure template. The resulting solid was filtered, washed and dried in air at room temperature, then calcined at 783 K in flowing nitrogen and air to remove the surfactant. The final composite was characterized using different techniques: Mössbauer spectroscopy (ME) at RT and 13 K, atomic absorption spectroscopy (AAE), X-ray diffraction (XRD) at low angles, N2 adsorption at 77 K (BET), Fourier transform infrared spectroscopy (FTIR), magnetization vs. magnetic field (M–H) measurements recorded at 6 and 300K. The obtained results indicate that the γ-Fe2O3 phase is still present in the final composite with a superparamagnetic behavior at RT. Besides, the composite has a large specific surface area (greater than 500 m2/g), a narrow pore diameter distribution with an average size of 2.6 nm. The XRD patterns at low angles indicate the presence of an ordered mesoporous structure of MCM-41 silica coating the magnetic γ-Fe2O3 NPs. The experimental results and the presence of free silanol groups of the silica pore surfaces, wich enables the composite functionalization with a wide variety of chemical agents, becomes this magnetic composite into an excelent material for potencial aplications in fields as adorbents, biomedicine and biomolecules separation.