In order to control the polarity of the gel material which requires a definite affinity for the solvent or solute so as to enable its reaction with the bonded phosphoric acid, the polymerization can be carried out with more or less of a material such as styrene, C1 to C18 alkyl methacrylate, C1 to C18 alkyl acrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, acryloylmorpholine,