Preparation of nanocomposite superabsorbents based on hydrotalcite and poly(acrylic-co-acrylamide) by inverse suspension polymerization

Firstly, hydrotalcite (HT) was synthesized by the urea method. Then, sodium methyl allyl sulfonate (SMAS) was used as intercalation agent to prepare intercalated HT (SMAS-HT). Finally, a novel poly(acrylic-co-acrylamide)/HT nanocomposite superabsorbent was prepared by inverse suspension polymerization, using N,N'-methylenebisacrylamide (NMBA) as a cross-linking agent and potassium persulfate (KPS) as an initiator. The morphology of the superabsorbents was characterized by FT-IR, XRD, SEM and TEM. The influences of the amount of SMAS-HT on the water (salt) absorbency were investigated. Results showed that the intercalation was successful and the intercalated SMAS-HT incorporated into the superabsorbent was completely exfoliated. The superabsorbent particles approach a spherical shape and the average size is 200-300 nm. The particle sizes of the superabsorbents decrease with increasing the content of SMAS-HT. In addition, the superabsorbent acquired its highest water (salt) absorbency when the content of SMAS-HT is 3 wt%. The highest absorbencies of the superabsorbent for deionized water and 0.9% NaCl(aq) were 900 g/g and 140 g/g, respectively.