Molecular Engineering Design Temperature Sensitive Atmospheric Water Harvesting Biomimetic Multiphase Gel

Abstract Atmospheric water harvesting (AWH) materials have emerged as promising and sustainable strategies to mitigate global freshwater scarcity. However, conventional hygroscopic salt/polymer composites are hindered by poor moisture sorption thermodynamics and sluggish desorption kinetics. Here, a molecularly engineered multiphase gel (PNIPAm‐co‐PAAS/PANI@LiCl) is synthesized via in situ copolymerization of sodium acrylate (AAS) and N‐isopropylacrylamide (NIPAm) on polyaniline (PANI) nanoparticles, followed by coordination with hygroscopic salt. The resulting gel mimics the hydrophilic/hydrophobic surface patterning found in biological systems. This hierarchical structure enables efficient water vapor capture via hydrophilic polymer networks and hygroscopic salts, while solar‐triggered desorption is enhanced by the thermal responsiveness of PNIPAm and the photothermal effect of PANI. The gel exhibits a water uptake capacity of 0.56–3.78 g g⁻ 1 across a broad humidity range (25–90% RH) and achieves a solar‐driven desorption rate of up to 2.5 kg m⁻ 2 h⁻ 1 . When integrated with an inverted passive cooling device, the system yields up to 2.2 g g⁻ 1 cycle⁻ 1 under real‐world outdoor conditions. This strategy overcomes key limitations of conventional AWH materials and offers a scalable, energy‐efficient solution for water harvesting across diverse humidity conditions.