The ion-adsorption and swelling behaviors of sulfobetaine hydrogels composed of N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) and N,N-dimethyl-(acrylamidopropyl)ammonium butane sulfonate (DMAABS) at various temperatures and cross-linker concentrations were investigated. We demonstrate a correlation between ion adsorption onto the DMAAPS gel and its degree of swelling. Conversely, in the DMAABS gel, the cross-linker concentration and temperature showed no effect on gel adsorption ability and swelling behavior. Furthermore, maximum ion adsorption onto the DMAAPS gel was strongly correlated with the transition temperature of the polymer. The carbon spacer length between the sulfobetaine charged groups mediates the interactions between the quaternary ammonium (R4N+) and sulfonate groups (SO3 −) that contribute to their adsorption, swelling, and transition behavior.
- Swelling behavior
- Transition temperature