Synthesis of a Novel Pectin-Based Superabsorbent Hydrogel with Salt and pH-Responsiveness Properties

Abstract

A novel smart superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid (AA) and acryl amide (AM) monomers onto pectin, using ammonium persulfate (APS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The graft copolymerization conditions were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM) and thermogravimetric analysis TGA. Results from SEM observation also showed a porous structure with smooth surface morphology of the hydrogel. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The pH-reversibility property of the hydrogels makes the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.