Na₂SO₄·10H₂O hydrogel for thermal management via synergistic phase change and evaporative cooling

With the increasing power density of integrated circuits challenging traditional passive heat dissipation, novel materials such as phase change hydrogel are often required. In this work, a biomimetic sweating phase change composite hydrogel is presented where a Co-N/O coordination structure is fabricated via the coordination reaction of CoSO₄·7H₂O and ethanolamine. The hydrated salt phase change material, Na₂SO₄·10H₂O, is embedded in a polyacrylamide matrix, and carbon nanotubes are introduced to construct a 3D thermal conduction pathway. During the phase change, Na₂SO₄·10H₂O absorbs heat and releases water for evaporative cooling. The Co-N/O structure, acting as a hygroscopic site, adsorbs ambient moisture when the system is inactive, promoting the hydration and regeneration of Na₂SO₄·10H₂O and enabling synergistic optimization. This composite hydrogel features a phase change enthalpy exceeding 130 J·g⁻¹. The addition of carbon nanotubes boosts its thermal conductivity by 107 % to 0.793 W·m⁻¹·K⁻¹. The Co-N/O structure significantly enhances its moisture absorption/desorption capabilities, with a moisture absorption rate of 4.71 g·g⁻¹ at 95 % relative humidity and a maximum water absorption rate of 2.7 g·g⁻¹·h⁻¹. At 30 % relative humidity, over 80 % of water is released within 50 min at 60 °C. In operation, it reduces the heating plate temperature by 8.6 °C and maintains a low temperature for 140 min, offering an efficient and eco - friendly solution for high - density electronic device heat dissipation.