Chemically crosslinked polycations carrying charges on the chain backbone, that is, x,y-ionene hydrogels (x = 2 or 6, y = 3 or 6), were successfully synthesized, and their swelling and surfactant binding behaviors were studied. A two-step surfactant binding that produced swollen, complex hydrogels occurred for ionene hydrogels with a lower charge density. The reswelling of the hydrogels was associated with an excessive amount of surfactant binding, which mainly occurred through a hydrophobic interaction with a one-to-one complex. (c) 2006 Wiley Periodicals, Inc.