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

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.