Aqueous chemical grafting of modified-PEG onto maghemite nanoparticles: Influence of grafting conditions

Abstract

The synthesis of maghemite nanoparticles coated with triethoxysilane- monomethylether-PEG (Si-mPEG), is presented in aqueous conditions, by the grafting to" process. This procedure is performed in one step, starting from anchored polymer and native nanoparticles. The maghemite nanoparticles obtained were first identified by XRD and the average diameter is about 10 nm according to the Nitrogen adsorption, XRD and TEM techniques. The nature of the catalysts (acetic acid, triethylamine, NH4OH and dibutyl-tin- dilaurate) used for the establishment of the covalent bond between the Y-Fe 2O3 particles and the Si-mPEG, as well as the influence of the temperature and the reaction time, were evaluated on the grafting rate of the particles in water by TGA and FTIR techniques. Using the size exclusion chromatography, SEC technique, we showed that the monomethoxy-PEG was resistant to mild acidic up to strong basic conditions. The best ratio "time/amount of polymer" for the highest grafting rate was the use of tin-based organometallic compound (DBTL) at 80 °C during 48 h. In these conditions, a grafting rate of 54 % is achieved.