Oxide-carbon composites and porous metal oxides prepared via water-swellable polymer networks

Water-swellable polymer networks (WSPN) were employed as media for lodging metal nitrate salts or partially hydrolyzed tetraethyl orthosilicate (TEOS), which are precursors for inorganic oxides. The loading was achieved either via the polymerization of a suitable monomer and a cross-linker in an aqueous solution of the precursor or, in the case of TEOS, via the simultaneous polymerization of both monomers. The pyrolysis of the precursor-loaded network under N-2 flow generated interpenetrating networks of carbon and metal oxide. The combustion of the composite in air removed the carbon network and a porous metal oxide framework remained. On the basis of this methodology, a coating layer of C-SiO2 composite was generated on a carbon-fiber, and porous powders of SiO2, ZrO2, MgO, and CuO-ZnO-Al2O3 oxide(s) were synthesized. It was found that the specific surface area of the oxides is affected by the nature of the WSPN. Two methodologies which lead to particles were developed. In one of them, sedimentation polymerization, large particles of about 1 mm size were obtained. In the other one, which starts from an emulsion of a water solution in an organic liquid (toluene, cyclohexane), micrometer size particles were prepared.