Scanning electron microscopy investigation of magnetite nanoparticles immersed in styrene-divinylbenzene mesoporous template

X-ray high-resolution scanning electron microscopy was used to investigate the spatial distribution of magnetite nanoparticles chemically synthetized in mesoporous styrene-divinylbenzene copolymer microspheres. The parabolic-like spatial-distribution of magnetite along the microsphere diameter (200 ?m average diameter) presents the lowest magnetite concentration at the microsphere center and the highest magnetite concentration at the microsphere surface. The magnetite spatial profile is claimed to be a result of normal diffusion of the chemical species throughout the porous template in contact with the aqueous solution during the incorporation step of the ferrous ions. We found that the aqueous-ion diffusion coefficient changes as the template is chemically-cycled from 1 to 15 cycles with the purpose of increasing the magnetite mass incorporation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)