Novel types of highly swelling hydrogels were prepared by grafting crosslinked polyacrylamide-co-poly-2-acrylamido-2-methylpropane sulfonic acid (PAAm-co-PAMPS) chains onto sodium alginate (Na-Alg) through a free radical polymerization method. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FM). The controlled release behavior of diclofenac sodium (DS) from superabsorbent polymer was fact investigated, and shown that the release profiles of DS from superabsorbent polymer were slow in simulated gastric fluid (SGF, pH 1.2) over 3 h, but nearly all of the injtial drug content was released in simulated intestinal fluid (SIF, pH 7.4) within 21 h after changing media. Overall the results demonstrated that biodegradable superabsorbent could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be potential candidates as an orally administrated drug delivery system. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 2015 2023, 2010