In this work, silica nanoparticles (nanosilica, SiO2) prepared through a sol-gel process were modified by 3aminopropyltrietoxy silane (APTES). The presence of organic groups in APTES grafted to surface of nanosilica was found by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoemission spectroscopy (XPS). The grafting content of APTES on the nanoparticles surface was determined is 2.66 wt. percent
5.54 wt. percent
6.89 wt. percent and 7.52 wt. percent corresponding to m-silica 5, m-silica 10, m-silica 15 and m-silica 20 samples. The calculated data according to XPS results indicated that there are one-half of the number of ethoxy groups reacted in the modification process. The above results showed that surface treatment of nanosilica with APTES were successful.