colloidal silica due to its easily homogeneous dispersion [8], tailorable surface properties [9], etc. Colloidal silica particles usually exist in the type of sols with water or alcohol as the dispersing medium. However, these silica sols can be directly used only in polymer latex or water-borne systems, not in solvent-based systems, since the nanosilica particles are generally hydrophilic; therefore they usually need to be modified for application in nonaqueous systems [10], [11] and [12]. Silane coupling agents (SCA) are generally selected as the modification agents for colloidal silica particles since the hydroxyl groups on the surfaces of colloidal silica particles can react with siloxane groups of SCA. The attachment of SCA molecules to colloidal silica particles can prevent the aggregation of the particles due to the steric repulsion of grafted organic groups. Meanwhile, some new functional groups such as alkyl, amine, epoxide, and vinyl groups can be also introduced by the modification [13], [14], [15], [16] and [17]. Although quite a few SCA molecules have been adopted to modify the surfaces of colloidal silica particles, the influence of the properties of SCA molecules on the properties of nanocomposite polymers has seldom been reported.