Nanocomposite of carboxymethyl cellulose and attapulgite as a novel pH-sensitive superabsorbent: Synthesis, characterization and properties

Grafting vinyl monomers onto natural polysaccharides and then compounding with inorganic nano-scale clays become a preferred method to derive superabsorbents because it afforded unique environmental and commercial advantages. In current work, a series of superabsorbent nanocomposites were prepared by radical solution polymerization of sodium carboxymethyl cellulose (CMC), partially neutralized acrylic acid (NaA) and attapulgite (APT) using ammonium persulfate (APS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a crosslinker. Fourier transform infrared spectroscopy (FTIR) spectra proved that NaA was grafted onto CMC backbone and APT participated in polymerization. APT nanofibrils were retained in nanocomposite and uniformly dispersed in the CMC-g–PNaA matrix as shown by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) analyses. The thermal stability and water absorption of the nanocomposites were improved due to the incorporation of APT. The water absorption and gel strength depends on the MBA concentration. The remarkable pH-sensitivity and time-dependent swelling behavior of the nanocomposite in aqueous solution of cetyltrimethylammonium bromide (CTAB) were observed and discussed.