MIT News June 15, 2023
Hygroscopic hydrogels are emerging as scalable and low-cost sorbents for atmospheric water harvesting, dehumidification, passive cooling, and thermal energy storage. However, devices using these materials still exhibit insufficient performance, partly due to the limited water vapor uptake of the hydrogels. Researchers in Germany synthesized hygroscopic hydrogels with extremely high salt loadings by tuning the salt concentration of the swelling solutions and the cross-linking properties of the gels. This resulted in unprecedented water uptakes at relative humidity. At 30% RH, the uptake exceeded previously reported water uptakes of metal–organic frameworks by over 100% and of hydrogels by 15%, bringing the uptake within 93% of the fundamental limit of hygroscopic salts while avoiding leakage problems common in salt solutions. By modeling the salt-vapor equilibria, the maximum leakage-free RH is elucidated as a function of hydrogel uptake and swelling ratio. According to the researchers their work can guide the design of hydrogels with exceptional hygroscopicity that enable sorption-based devices… read more. Open Access TECHNICAL ARTICLEÂ
