Anti-shrinkage Rigid Macroporous Hydrogel with Dual Osmotic-Capillary Pumping for Ultra-Fast Atmospheric Water...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Hygroscopic hydrogels show promise for atmospheric water harvesting (SAWH).
• Their application is limited by slow water transport in dehydrated polymer networks, primarily due to osmotic pressure gradients.
• Conventional hydrogels struggle with structural collapse during dehydration, hindering water transport.

Purpose of the Study:

• To develop a rigid-polymer-network-based hygroscopic hydrogel (H_RIMP) with ultrafast sorption/desorption kinetics.
• To overcome the mass-transfer limitations of conventional hydrogels for high-efficiency SAWH.
• To demonstrate a continuous cyclic SAWH device utilizing the novel hydrogel.

Main Methods:

• Developed a rigid-polymer-network-based interconnected macroporous hygroscopic hydrogel (H_RIMP).
• Employed a foaming-assisted polyelectrolyte diffusion-complexation strategy.
• Investigated the hydrogel's sorption/desorption kinetics and water productivity in a cyclic SAWH device.

Main Results:

• The H_RIMP exhibits ultrafast sorption/desorption kinetics, reaching equilibrium water uptake rapidly across various relative humidity levels.
• The rigid network prevents structural collapse, facilitating synergistic water transport via osmotic pressure and capillary pumping.
• The SAWH device achieved high water productivity (1.07 L_water kg_sorbents^-1 day^-1) under cold, dry conditions (0 °C, 43% RH).

Conclusions:

• The rigid-network design strategy effectively overcomes mass-transfer limitations in gel-based adsorbents.
• H_RIMP demonstrates superior performance for high-efficiency SAWH, even in challenging environmental conditions.
• This approach offers a generalizable pathway for advancing practical SAWH systems.