Hygroscopic Zwitterionic Fabrics for Sustainable Atmospheric Water Harvesting

Hygroscopic polymer gels have emerged as promising moisture sorbents for atmospheric water harvesting (AWH) adaptable to diverse climatic and geographic conditions. However, their application is often hampered by limited mechanical flexibility, robustness, and slow adsorption kinetics due to their highly crosslinked networks. Herein, a new class of AWH sorbent—hygroscopic zwitterionic fabrics (HZFs)—is developed by grafting crosslinking‐free zwitterionic polymer brushes onto cotton fabrics through surface‐initiated atom transfer radical polymerization, followed by LiCl loading through electrostatic interactions. The resulting HZFs exhibit excellent mechanical flexibility, sufficient robustness, and scalability, along with superior moisture uptake capabilities at various relative humidity (RH) levels and mitigated salting‐out effect. Leveraging these features, a novel AWH prototype is designed that utilizes a single HZF layer for atmospheric water adsorption and a compact, stacked configuration of multiple HZF layers for effective water desorption. Real‐world outdoor tests demonstrate a daily water production of 4.2 L H2O ·m −2 HZF (33.8–17.3 °C, 15.2–60.0% RH), highlighting the great potential of HZFs‐based device for efficient AWH under various climatic conditions. Grafting crosslinking‐free polymer brushes onto fabrics presents a novel engineering approach for developing high‐performance AWH sorbents, paving a promising way for sustainable and scalable water harvesting solutions.