Multi-scale synergistically optimized PNIPAM-co-PAAS/non-woven fabric composite hydrogels for efficient atmospheric water harvesting

Atmospheric water harvesting (AWH) is a sustainable solution to freshwater scarcity, yet balancing sorption capacity, energy efficiency, and stability remains challenging. Herein, we developed a multi-scale synergistically optimized composite sorbent (NW-NA@PDA-Cl) by integrating a poly (N-isopropylacrylamide)- co -poly (sodium acrylate) (PNIPAM- co -PAAS) copolymer network onto a non-woven (NW) fabric scaffold. Hierarchical diffusion channels were constructed via freeze-drying to accelerate mass transfer, while a polydopamine (PDA) coating facilitated molecular-level anchoring of lithium chloride (LiCl) through coordination and electrostatic interactions, effectively suppressing salt leakage. NW-NA@PDA-Cl achieved exceptional sorption capacities of 1.26 and 3.11 g g - 1 at 30% and 90% relative humidity (RH), respectively. Benefiting from the thermoresponsive restructuring of the hydrogen-bonding network, the material exhibited rapid desorption kinetics (78.6% release within 20 min at 60 °C) and a significantly reduced evaporation enthalpy (1536.5 J g - 1 ). Under 1.0 sun, photothermal effects drove surface temperatures to 65 °C, enabling efficient passive water recovery. Field tests demonstrated a daily yield of 1.27 g g - 1 day - 1 with drinking-standard water quality. This multi-scale design strategy provides a promising pathway for developing high-performance, energy-efficient, and stable AWH systems.