The modi. cation of nano-fibriform silica by dimethyldichlorosilane was studied by transmission electron microscopy, X-ray powder diffraction, infrared spectroscopy, Raman spectroscopy, physical N-2 adsorption techniques, differential thermal and thermogravimetric analysis, scanning electron microscopy, and elemental analyzer. The results show that dimethyl silane derivatives have been successfully covalently grafted on nano fibriform silica. The polarity of the modified product decreases with the substitution of -OH groups by siloxyl groups. Therefore, the modified product can be easily dispersed in organic solvent and its compatibility with organic molecules is improved. After modi. cation the pore volume decreases and the ductility greatly increases, indicating that the modified product is of a higher strength than before. The study demonstrates that the modified product can be used as an ideal additive to reinforce the strength of organic materials. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.