Study Effect of Various Environmental Conditions on the Swelling Property of Biocopolymer Based on Carrageenan-g-polyMethacrylic acid Hydrogel

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In this study, a series of highly swelling hydrogels based on carrageenan and polymethacrylic acid (PMAcA) was prepared via a free radical polymerization method. The graft copolymerization 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 Infrared spectroscopy was carried out to confirm the chemical structure of the composite. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). Absorbency in various aqueous salt solutions indicated that the swelling capacity decreased 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 salt solutions, the hydrogels may be referred to as anti-salt superabsrbents. The swelling behavior of superabsorbing hydrogels was also measured in solutions with pH ranged from 1 to 13.

Carrageenan; Superabsorbent; Swelling behavior; Methacrylic acid monomer