Synthesis of a biocopolymer carrageenan-g-poly(AAm-co-IA)/ montmorilonite superabsorbent hydrogel composite

a novel superabsorbent hydrogel composite based on kappa-carrageenan (κc) has been prepared via graft copolymerization of acrylamide (aam) and itaconic acid (ia) monomers in the presence of montmorolonite clay powder, methylenebisacrylamide (mba) as the crosslinking agent and ammonium persulfate (aps) as initiator. evidence of grafting and montmorolonite interaction was obtained by comparison of ftir and tga spectra of the initial substrates and the superabsorbent composite. a new absorption band at 1722 cm-1 in the composite spectrum confirmed montmorolonite-organic polymer linkages. moreover, the morphology of the samples was examined by scanning electron microscopy (sem). the swelling of the superabsorbing hydrogels was also examined in solutions with ph values ranging between 1.0 and 13.0. finally, the swelling behavior of these composite polymers was investigated in various salt solutions. results indicated that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. this behavior can be attributed to the charge screening effect of monovalent cations, as well as ionic crosslinking for multivalent cations.