Modification of Na-bentonite by polycations for fabrication of amphoteric semi-IPN nanocomposite hydrogels

Na-bentonite was modified by intercalation of poly(dimethyldiallylammonium chloride) (PDMDAAC). The XRD pattern and TEM image indicated that an exfoliated nanocomposite was obtained. Then, graft polymerization of acrylic acid onto starch was carried out to form an amphoteric nanocomposite hydrogels with semi-interpenetrating polymer networks (semi-IPN) in the dispersion of the nanocomposite. The swelling behavior of the hydrogels was studied in buffer solution at different pH. The amphoteric semi-IPN hydrogels had excellent pH-sensitivity in the range of pH from 2 to 4. The amphoteric semi-IPN hydrogels exhibited excellent compressive strength even at high water content.