Thermosensitive superabsorbents based on poly(N,N-diethylacrylamide-co-sodium acrylate)

A series of poly(N,N-diethylacrylamide-co-sodium acrylate) with a degree of crosslinking of 1 mol% have been prepared as thermosensitive superabsorbents for water. The critical swelling temperatures or the volume phase transition temperature (VPTT) and the water absorption capacity of the polymers can be modulated by varying the amount of sodium acrylate (0-60 mol%) in the copolymers. The water absorption and swelling properties of the different hydrogels have been studied as function of temperature. The crosslinked copolymers can absorb large amounts of water at ambient temperatures and dehydrate at higher temperatures with relative ease, making the absorbent materials thermally responsive and thus reusable. The water absorption capacity of the copolymers depends on the pH of the media as the acrylate monomer has a higher water absorption in its deprotonated state. Added urea in the media raises and sharpens the VPTT values of the copolymers containing sodium acrylate.