Synthesis and Swelling Behavior of Starch-Poly (Sodium Acrylate-co-Acrylamide) Superabsorbent Hydrogel

Superabsorbent polymers based on starch (St ) and polyacrylonitrile (PAN) were prepared by alkaline hydrolysis of the physical mixture of St and PAN inaqueous solution. The nitrile groups of PAN were completely converted to a mixture of hydrophilic carboxamide and carboxy late groups during alkaline hydrolys is, followed by in situ cross-linking of the PAN chains by the alkoxideions of St . A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR spectroscopy. Moreover , morphology of the samples was examined by scanning electron microscopy. The factors that influenced the swelling capacity of the hydrogels were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Further more, the salt sensitivity of the hydrogels was investigated in different saline solutions . The pH-rever sibility and on-off swit ching properties of the hydrogels make the intelligent polymers good candidates for consideration as potential carriers of bioactive agents. Finally, the swelling and de-swelling kinetics behaviors of the hydrogels were preliminarily investigated as well.