Potential Environmental Application of a Tough and Temperature-Responsive Nanocomposite Hydrogel Based on Poly(N-Isopropylacrylamide-co-Sodium Methacrylate) and Clay

Abstract

A simple method was proposed to prepare a tough and ultra-extensible hydrogel with ultra-fast response to temperature and pH and a high potential to adsorb heavy metals by utilizing poly (N-isopropyl acrylamide) (PNIPAm), sodium methacrylate (SMA), and the crosslinking process using Laponite RDS clay. Transmission electron microscopy was used to examine the distribution of clay in the hydrogels. The hydrogels' exceptional mechanical and tensile qualities are a result of the precise physical crosslinking caused by Laponite RDS clay and the ultra-long polymer chains that were produced because of the selected polymerization conditions. A tiny quantity (1.5 mol%) of SMA co-monomer adds a strong pH response and improves the effectiveness of metal removal, whereas PNIPAm produces clearly defined temperature responsiveness. In the meantime, as the SMA content increased, the equilibrium swelling increased, but when the loading of Laponite RDS clay increased, it decreased. It has been shown that hydrogels can effectively adsorb Cr(VI) from aqueous solutions. The removal effectiveness and stability of the hydrogels were enhanced by adding SMA, with efficiency values reaching 99.93%. Given their great swelling, mechanical toughness, and high Cr(VI) removal efficiency, the investigated hydrogels appear highly suitable as an adsorbent for water treatment.