Molecular Design of Thermally Responsive Metal Affinity Hydrogels for Contaminant Detection and Removal from Wastewater

Environmentally sensitive hydrogels have the ability to filter large quantities of water in their swollen state and shrink to a compact form in the collapsed state. Combining this property with affinity groups offers the potential of a material with excellent properties for waste water treatment. However, the addition of other groups usually diminishes the environmentally sensitive swelling properties. In this study a method is developed to overcome these limitations employing the monomer N-isopropyl acrylamide (NIPAAm) and a metal affinity group. Employing a molecular design approach and carefully balancing the hydrophobic and hydrophilic groups a new co-monomer was synthesized and copolymerized with NIPAAm to produce an affinity hydrogel. By controlling the fraction of the co-monomer and the crosslinker it is shown that this hydrogel can be made to mimic the thermally sensitive phase transition behavior of pure NIPAAm hydrogels. The gels also retain strong metal affinity with similar to 75% of the affinity groups binding to copper ions.