Silanation and stability of 3-aminopropyl triethoxy silane on nanosized superparamagnetic particles: I. Direct silanation

The direct silanation of nanosized superparamagnetic particles (gamma-Fe2O3) using 3-aminopropyl triethoxy silane is described. The silanized films are characterized using X-ray photoelectron spectroscopy, diffuse-reflectance Fourier transform infrared spectroscopy and electrokinetics. The silanation is conducted in both organic (toluene) and water solutions to examine the solvent effect on the molecular orientation and packing density of the silanized films. Depending on the solvent, about 74 to 83% of amine groups are found to be un-protonated and remain reactive on the particles. In acidic environment, the films silanized in toluene are more stable than that in water, but both are unstable in basic environment. (C) 1997 Elsevier Science B.V.