Superabsorbent polymeric materials VII: Swelling behavior of crosslinked poly[sodium acrylate-CO-trimethyl methacrylamido-propyl ammonium iodide] in aqueous salt solutions

A series of xerogels based on sodium acrylate (SA), cationic comonomer trimethyl methacrylamidopropyl ammonium iodide (TMMAAI), and N,N-methylene-bis-acrylamide (NMBA) were prepared by inverse suspension polymerization. The water absorbency and the swelling behavior for these highly absorbent polymers in deionized water and various saline solutions were investigated. Results indicated that the water absorbency increased when a small amount of TMMAAI monomer was introduced into the SA gel. The water absorbency decreased with increase in TMMAAI content, but the contrary result was observed for initial absorption rate. Moreover, with more crosslinking agent, the water absorbency was lower. Finally, the adsorption of copper ion by these gels was also investigated.