Dynamic Hydrogen Bond Evolution in Thermosensitive Hydrogels for Self-Adaptive Passive Cooling

Abstract

Facing the growing demand for green cooling, the application of thermosensitive hydrogels in adaptive thermal management is limited due to the kinetic-thermodynamic mismatch of water molecules during their phase transition. Herein, we propose a dynamic gradient hydrogen bonding hydrogel (hydrogen bonding energy in P(NAGA-CO-NIPAm hydrogel showing a gradient with increasing temperature) via artificial intelligence (AI) assisted component optimization to construct thermosentive hydrogels with hierarchical synergistic dissipative pattern, which combine both phase-volume stability and optical transition properties, enabling adaptive passive cooling. The P(NAGA-CO-NIPAm)-4* thermosensitive hydrogel possesses a triple synergistic mechanism (dynamic hydrogen bonding, hydrophobic aggregation, and light scattering) and exhibits excellent adaptive evaporative cooling capability (5°C: 21.97 W/m² → 25°C: 53.99 W/m² → 45°C: 608.94 W/m²), which effectively solves the mismatch between water-molecule transport dynamics and material thermodynamic response. At 45 °C, the cooling duration of P(NAGA-CO-NIPAm)-4* hydrogel exceeded that of conventional PNIPAm hydrogels by over 10-fold. Compared to PNAGA and PNIPAm, P(NAGA-CO-NIPAm)-4* exhibits the best cooling capacity in extreme environments (60°C and 800 W/m²) , cooling to 41.33°C (ΔT = 17.44°C, 29.68%). The results provide a theoretical foundation and practical framework for next-generation adaptive cooling materials, with significant scientific and practical value in mitigating global cooling demands.