Tractable metal oxide sols are made by combining at least one metal oxide compound, at least one organofunctional silane, at least one boron oxide compound, and a liquid, or metal oxide sols are made by combining at least one metal oxide compound, at least one organofunctional silane, at least one of an acid catalyst and salt/complex catalyst, and a liquid. Also disclosed are nanocomposites containing the metal oxide 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 metal oxide sol and the nanocomposite.