Hygroscopic, Creatine-Functionalized Microgels for Efficient Desiccants and Water Harvesting

Atmospheric water is an attractive source of potable water that can alleviate global water scarcity. In this work, we present a series of poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (poly(NIPAAm-co-HEMA)) microgels as viable thermoresponsive water-harvesting materials. Directed modifications on microgel composition and size yielded water uptake of up to 450 mg of water per g of polymer after 1 h. Thermoresponsive properties were observable below 35 °C. We also conducted creatine postfunctionalization on microgels, which removed thermoresponsive properties but increased water uptake to 1.8 g/g after 1 h. Water uptake–release cycling experiments yielded 9.8 g/g per day with 50 min cycles. The data in this body of work showcase a microgel material for atmospheric water harvesting and present the potential of microgels as a class of water harvesting materials.