Preparation and Properties of Chitosan-g-poly(acrylic acid)/Montmorillonite Superabsorbent Nanocomposite via in Situ Intercalative Polymerization

A novel chitosan-g-poly(acrylic acid)/montmorillonite superabsorbent nanocomposite with water absorbency of 160.1 g g-1 in distilled water and 46.6 g g-1 in 0.9 wt % NaCl solution was prepared by in situ intercalative polymerization among chitosan, acrylic acid, and montmorillonite in aqueous solution, using N,N'-methylenebisacrylamide as a cross-linker and ammonium persulfate as an initiator. Chitosan could intercalate into layers of montmorillonite and form superabsorbent nanocomposites through in situ graft-polymerization with acrylic acid according to XRD, IR spectra, TEM, and SEM analysis. The one-step method is more convenient, and the corresponding nanocomposites have higher swelling ability and pH-responsivity as compared to the two-step method. Factors influencing water absorbency of the superabsorbent nanocomposite were investigated, such as weight ratio of acrylic acid to chitosan and montmorillonite content. The introduced montmorillonite could form a loose and porous surface and improve water absorbency of the chitosan-g-poly(acrylic acid) superabsorbent.