Kinetics of Sorption in Hygroscopic Hydrogels
Author(s)
Díaz-Marín, Carlos D; Zhang, Lenan; Lu, Zhengmao; Alshrah, Mohammed; Grossman, Jeffrey C; Wang, Evelyn N; ... Show more Show less
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Hygroscopic hydrogels hold significant promise for high-performance atmospheric water harvesting, passive cooling, and thermal management. However, a mechanistic understanding of the sorption kinetics of hygroscopic hydrogels remains elusive, impeding an optimized design and broad adoption. Here, we develop a generalized two-concentration model (TCM) to describe the sorption kinetics of hygroscopic hydrogels, where vapor transport in hydrogel micropores and liquid transport in polymer nanopores are coupled through the sorption at the interface. We show that the liquid transport due to the chemical potential gradient in the hydrogel plays an important role in the fast kinetics. The high water uptake is attributed to the expansion of hydrogel during liquid transport. Moreover, we identify key design parameters governing the kinetics, including the initial porosity, hydrogel thickness, and shear modulus. This work provides a generic framework of sorption kinetics, which bridges the knowledge gap between the fundamental transport and practical design of hygroscopic hydrogels.
Date issued
2022-01-21Department
Massachusetts Institute of Technology. Department of Mechanical Engineering; Massachusetts Institute of Technology. Department of Materials Science and EngineeringJournal
Nano Letters
Publisher
American Chemical Society (ACS)
Citation
Díaz-Marín, Carlos D, Zhang, Lenan, Lu, Zhengmao, Alshrah, Mohammed, Grossman, Jeffrey C et al. 2022. "Kinetics of Sorption in Hygroscopic Hydrogels." Nano Letters.
Version: Author's final manuscript