Fast-swelling porous starch-g-poly(acrylic acid) superabsorbents

The fast-swelling porous starch-g-poly(acrylic acid) (St-g-PAA) superabsorbents were prepared simply by free-radical graft polymerization between acrylic acid and potato starch in the aqueous phase by using Triton X-100 as the pore-forming agent. The porous superabsorbents were characterized by FTIR and scanning electron microscopy. The effects of weight ratio of acrylic acid to starch and the Triton X-100 content on water absorbency were investigated. In addition, the effects of Triton X-100 on swelling rate, water absorbency in 0.9 % NaCl and in the artificial urine solution, and reswelling ability were studied in detail. The superabsorbent prepared with an acrylic acid/starch ratio of 6:1 and a Triton X-100 content of 0.4 % has a water absorbency of 683 g g−1 in distilled water and 72.8 g g−1 in 0.9 % NaCl. The content of Triton X-100 has great influence on the water absorbency and the swelling rate. The porous sample prepared with 0.4 % Triton X-100 only needs about 5 min to reach 80 % of its equilibrium water absorbency which is obviously shorter in comparison with the nonporous sample (about 90 min). The porous samples also show nice urine absorbency and excellent reswelling ability. We believe the reported method may find some applications in preparing novel porous hydrogels.