Nanocomposites based on poly(acrylamide-co-acrylate) and cellulose nanowhiskers

Superabsorbent hydrogels, based on poly(acrylamide-co-acrylate) filled with cellulose nanowhiskers (CNWs), were synthesized by free-radical aqueous copolymerization, using N,N-methylenebisacrylamide (MBAAm), as crosslinker, and potassium persulfate (K2S2O8), as initiator. A series of hydrogels was synthesized varying the percentage of CNWs (1, 2, 5, 10, and 20 wt.%) and the amount of crosslinking agent (0.05, 0.10, 0.15, and 0.20 mol.%). The hydrogels were characterized by FTIR and XRD techniques and their morphologies were investigated by SEM images. Superabsorbent hydrogel with Weq > 1195 image/ggel was obtained with percentage of 10 wt.% of CNWs and 0.05 mol.% of crosslinking agent. The hydrogel showed to be responsive to the pH-variation (2–12) and also to the presence of salts (NaCl, KCl, MgCl2, and CaCl2). The hydrogel exhibited a pH-responsiveness and cation-sensitivity character so that a swelling–deswelling pulsatile behavior was recorded at pH 2–8 as well as cycles of hydrogel immersion in sodium and calcium salts solutions.