Study on Preparation and Properties of Poly(ethylene glycol)-Modified Nano-SiO2

In this article, low-molecular-weight poly(ethylene glycol) (PEG) was grafted onto the surface of nano-silica particles by a two-step process. The nano-silica particles were firstly reacted with thionyl chloride, and then modified with PEG. The composite structure was investigated by FT-IR spectroscopy, X-ray Photoelectron Spectrum (XPS), Differential Thermal Analysis (DTA) and Thermogravimetry Analysis (TGA). The peaks for alkyl group of PEG appeared at 1348 cm(-1), 1459 cm(-1) and 2870 cm(-1) in FI-IR. The XPS results also indicated that the -CH2- structure existed in the composites. As showed in the DTA and TGA figures, the organic structure decomposed at 400 degrees C and lost about 40% weight. So we can calculate that the grafting percentage was about 40%.