Department of Chemistry, Science FacultyIslamic Azad University,Arak Branch Arak Iran

Email:- m-sadeghi@iau-arak.ac.ir

In this study, a series of highly swelling hydrogels bassed on sodium alginate (NaAlg) and polyN-Isopropylacrylamide (PNIPAAm) was prepared via a free radical polymerization method. The graft copolymezation reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'- methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established usingFTIR spectroscopy, Absorbency in various aqueous salt solution indicated and the swelling capacity deceased with an increase in the ionic strength of the swelling medium. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. However, due to the high swelling capacity in the solutions, the hydrogels may be referred to as antisalt superabsorbents, Meanwhile, the overall activation enegy for the crosslinking reaction between Alg polysaccharrides was estimated to be 18.9kj/mol.