The method of claim 7 wherein C is a compound selected from the group consisting of maleic anhydride; succinic anhydride; phthalic anhydride; tetrahydrophthalic anhydride; hexahydrophthalic anhydride; butane succinic anhydride; trimellitic anhydride; glutaric anhydride; itaconic anhydride; chlorendic anhydride; methyl hexahydrophthalic anhydride; methyl tetrahydrophthalic anhydride; ethylene oxide