Graft copolymerization of sodium acrylate onto organophilic montmorillonites initiated by potassium diperiodatonickelate (IV) and application of graft copolymer in water‐superabsorbent

The graft copolymerization of sodium acrylate (SA) onto organophilic montmorillonites (OMMT) initiated by redox reaction of potassium diperiodatonickelate (IV) Ni(IV)] with reactive groups on OMMT substrate was studied in alkaline medium. The grafting parameters have been investigated as a function of the ratio of monomer to OMMT, the concentration of initiator, temperature, and pH value. The structure of the graft copolymer (OMMT‐g‐PSA) was systematically characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscope (SEM). It was found that Ni(IV)] belongs to a highly efficient initiator for graft copolymerization of SA onto OMMT via the redox iniation (grafting efficiency > 95%). Furthermore, the experimental results also showed that the graft copolymer gels synthesized under optimal condition exhibited a maximum water absorbency of 1104 g/g in distilled water and 111 g/g in 0.2 wt % NaCl solution, respectively, and its water retention ability is more than 91% after centrifugal separation for 2 h. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008