Swelling of poly(vinyl amine) gels: Applicability of the Donnan theory

The volume swelling behaviors of poly(vinyl amine) (PVAm) gels were predict ed on the basis of the Donnan theory with the ionic strength of KCI solutio ns at three different pH (acidic, basic, neutral solution). At neutral (pH 7) and basic (pH II) conditions, maximum volume swellings were observed in the intermediate concentration of KCl due to the difference in the ionic sw elling pressure with the salt concentration. On the contrary, at acidic (pH 3) condition, maximum volume swelling was not found. This was attributed t o the full dissociation of the amino groups of PVAm gels even at very low c oncentration of KCl. In the comparison of the experimental results with the theoretical ones, the experimental results agreed fairly well with the sim ple Donnan theory, verifying a possible application of the Donnan theory to the prediction of the cation-typed gels.