Superabsorbent polymeric materials IX: Effect of cationic structure on swelling behavior of crosslinked poly(sodium acrylate-co-cationic monomers) inaqueous salt solutions

Two series of xerogels based on sodium acrylate (SA), trimethyl methacrylam idopropyl ammonium iodide (TMMAAI), trimethyl methacryloyloxyethyl ammonium iodide (TMMAI), and N,N ' -methylene-bis-acrylamide (NMBA) as a crosslinke r were prepared by inverse suspension polymerization. The water absorbency and swelling kinetic behavior for these xerogels in water or various saline solutions were investigated. The results showed that the swelling behavior s of these absorbents are related to their chemical structures, their compo sitions, and the type of external salt solutions. There would be effective improvement in the water absorbency of these two gel series by copolymerizi ng SA with a small amount of cationic monomer (TMMAAI or TMMAI). The initia l absorption rates in deionized water were found to be faster for TM series gels than for TA series gels. The two series of superabsorbents had a tend ency to absorb water in dilute nitrate aqueous solutions in the order: Fe3, Ni2+, Ca2+, Cu2+, and Na+ for Fe(NO3)(3), Ni(NO3)(2), Ca(NO3)(2), Cu(NO3) (2), and NaNO3 aqueous solution, respectively. The absorbency and initial a bsorption rate for these gels were related to the gel compositions and salt concentrations. (C) 2001 John Wiley & Sons, Inc.