Disclosed are silica sols made by combining at least one hydrolysable silane, at least one organofunctional silane, at least one boron oxide compound, and a liquid, or silica sols made by combining at least one hydrolysable silane, at least one organofunctional silane, at least one acid catalyst, and a liquid to provide an intermediate sol and combining at least one base catalyst with the intermediate sol. Also disclosed are nanocomposites containing the silica sols and at least one of metal nanoparticle, metal-chalcogenide nanoparticle, metal oxide nanoparticle, and metal phosphate nanoparticle. Further disclosed are composites containing a polymer material and at least one of the silica sol and the nanocomposite.