Thermoreversible hydrogels XI: Effect of salt on the swelling properties of the (N-isopropylacrylamide-co-sodium 2-acrylamido-2-methylpropyl sulfonate) copolymeric hydrogels

The swelling behavior for a series of NIPAAm/NaAMPS copolymeric hydrogels w ith polyelectrolytic and thermosensitive properties was investigated in var ious saline solutions. The swelling ratios for the present copolymeric hydr ogels were affected by the saline solution, which is the result of the neut ralization of the cations in the external solution with the negative charge s on the polymeric side chains. The adsorption of aniline by the gels incre ased when the temperature was higher than the gel transition temperature, a nd this result showed that, when the gels were in hydrophobic state, the hy drophobic organic molecules were more easily adsorbed onto the gels. (C) 20 00 John Wiley & Sons, Inc.