Toward Environmentally Robust Transpiration Cooling of High-Heat-Flux Electronics via Hydrogen-Bonded Sodium Polyacrylate/Glycerol Hydrogel Particles

Abstract The hydrogel-based transpiration cooling holds promise for thermal management of high-heat-flux electronics, yet its practical application is constrained by an inherent trade-off between high swelling capacity and environmental stability against dehydration and freezing. Here, this trade-off is decoupled by incorporating glycerol into a three-dimensional sodium polyacrylate (PANa) network. Glycerol modulates the water state within the polymer network via hydrogen bonding with both polymer chains and water molecules, enabling reduced water loss while preserving water for swelling and cooling. The resulting sodium polyacrylate/glycerol (PANa/Gly-3) hydrogel particles, prepared with a glycerol-to-water volume ratio of 1:1, exhibit a weight retention of 93.5% ± 0.7% after 12 h at 25 °C and 70% RH, excellent freeze resistance by remaining unfrozen at −23 °C for 45 days, and a high swelling ratio of 284 ± 3 g·g–1. Under a simulated high heat flux of 16 kW·m–2, PANa/Gly-3 hydrogel particles achieved cyclic transpiration cooling with a maximum temperature reduction of 30–33 °C and improved temperature uniformity across the heater surface compared with PANa particles. This study demonstrates an effective strategy that improves the environmental stability of PANa hydrogels while largely preserving their swelling capacity and mitigating local drying during transpiration cooling, thereby offering a promising solution for efficient thermal management of high-heat-flux electronics.