Organic/Inorganic Superabsorbent Hydrogels Based on Xylan and Montmorillonite

Abstract

The unique organic/inorganic superabsorbent hydrogels based on xylan and inorganic clay montmorillonite (MMT) were prepared via grafting copolymerization of acrylic acid (AA) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) with N , N ‐methylenebisacrylamide (MBA) as a cross‐linking agent and potassium persulfate (KPS) as an initiator. The effect of variables on the swelling capacity of the hydrogels, such as the weight ratios of MMT/xylan, MBA/xylan, and AMPS/AA, was systematically optimized. The results indicated that the superabsorbent hydrogels comprised a porous cross‐linking structure of MMT and xylan with side chains that carry carboxylate, carboxamide, and sulfate. The hydrogels exhibit the high compressive modulus ( E ), about 35–55 KPa, and the compression strength of the hydrogels increased with an increment of the MMT content. The effect of various cationic salt solutions (LiCl, CaCl 2 , and FeCl 3 ) on the swelling has the following order: Li + > Ca 2+ > Fe 3+ . Furthermore, the influence of pH values on swelling behaviors showed that the superabsorbent composites retained around 1000 g g −1 over a wide pH range of 6.0–10.0. The xylan‐based hydrogels with the high mechanical and swelling properties are promising for the applications in the biomaterials area.