Entanglement-Enhanced Sponge Hydrogels for High-Efficiency Atmospheric Moisture Harvesting

YN Hu and JJ Sun and ZX Wu and RF Zhou and P Xiao and JC Gu and T Chen, SMALL, 21 (2025).

DOI: 10.1002/smll.202512457

Atmospheric water harvesting (AWH) is a promising strategy for freshwater production. Although hygroscopic polymeric gels (HPGs) are attractive AWH materials, their performance is limited by slow sorption- desorption kinetics. Herein, a new strategy is proposed to enhance moisture sorption-desorption kinetics by engineering an entanglement- enhanced sponge hydrogel doped with lithium chloride (denoted as X-D- PP@LiCl), which is synthesized via cosolvent-induced gelation. By adjusting the dimethyl sulfoxide/water ratio (X-D), the cross-linking density of the poly(dimethylaminopropyl methacrylamide sulfonate) (PDMAPS) network is modulated, thereby constructing continuous microchannels. Such architectures enhance vapor diffusion efficiency while maintaining excellent structural integrity over multiple sorption- desorption cycles. Crucially, the synergy between PDMAPS and LiCl generates an internal osmotic pressure gradient, facilitating water transport and enabling continuous regeneration of active sites. Therefore, the X-D-PP@LiCl hydrogel exhibits outstanding water uptake rates (0.95-1.48 g g(-1) h(-1)) across a wide relative humidity (RH) range of 20-90%, a rapid desorption rate of 7.57 g g(-1) h(-1) at 30% RH, and robust cycling stability, retaining >97.6% of its initial water uptake capacity at 30% RH after 30 cycles. Furthermore, it achieves an excellent outdoor water production of 4.15 L kg(-1) day(-1). This work provides a new strategy for designing high-performance HPGs for AWH applications.

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