SWELLING BEHAVIORS OF AMPHOTERIC GELS AND THE DISSOCIATION MECHANISMS

Various types of amphoteric gels were made with the combinations of anionic monomers (sodium acrylate and sodium styrenesulfonic acid and cationic monomers (dimethylaminopropyl acrylamide and trimethyl-n-acryloly-3-aminopropane ammonium chloride) and the pH-dependent volume behaviors of these amphoteric gels were examined. As a consequence, the specific binding formed in each amphoteric gel could be dissociated into ions in a unique fashion with changes in pH. Four types of dissociation mechanisms could be presumed as follows; 1) ionization of the constituent groups (weak anion and cation groups) in both acidic and alkali solutions, 2) ionization of the constituent group (strong anion groups) in alkali solution, 3) ionization of the constituent group (strong cation groups) in acidic solution, and 4) ionization of the constituent groups (strong anion and cation groups) in both acidic and alkali solutions.