An amphoteric semi-IPN nanocomposite hydrogels based on intercalation of cationic polyacrylamide into bentonite

Amphoteric semi-interpenetrating polymer network nanocomposite (semi-IPN-NC) hydrogels were prepared by graft polymerization of acrylic acid onto starch in cationic polyacrylamide/bentonite nanocomposite aqueous dispersion. Cationic polyacrylamide (CPAM) was used as both an intercalating agent to enlarge interlayer space and a linear polymer chain to fabricate the semi-IPN structure. XRD and TEM confirmed a successful intercalation of CPAM into bentonite. Polymerization temperature was monitored in an attempt to explain the dependence of swelling on the polymerization conditions. The results showed that the hydrogel was of a high swelling and compressive strength even under water content of more than 99%.