• hydrogel;
  • swelling;
  • graft copolymer;
  • kinetic


Swelling behaviors of a starch-based amphoteric superabsorbent hydrogel cationic starch/sodium acrylate (CAS/AA) with quaternary ammonium and carboxyl groups were studied by immersion of the gels in various salt and pH solutions. It was found that swelling behaviors are heavily dependent of feed composition. Besides, it is also sensitive to pH, the concentration, and the ionic charge of the saline solution, but not to temperature. A kinetic study disclosed that the water transport mechanism in the CAS/AA was controlled by polymer relaxation. CAS/AA gels showed a good reversibility in the 0.9% NaCl solution after repeating the absorb-dry process for more than 20 times. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1995–1999, 2006