Soft photonic hydrogel interfaces for autonomous and dynamic thermoregulation

Adaptive passive cooling offers an energy-efficient approach to thermal management by dynamically responding to changes in solar irradiation, temperature, and humidity without external power input. However, existing adaptive thermoregulation materials remain limited by structural-mechanical mismatches in rigid multilayer architectures and weak coupling among optical, sorption, and mechanical functions. Here, we report a soft photonic hydrogel interface whose adaptive thermal regulation performance arises from the coordinated roles of a zwitterionic polymer network, hexagonal boron nitride (hBN), and aluminum oxide (Al₂O₃). The zwitterionic chains provide strong mid-infrared emission, high moisture affinity, conformal adhesion, and immobilization of hygroscopic lithium chloride (LiCl) salts; hBN nanoplates enhance broadband solar scattering and thermal transport; and Al₂O₃ nanoparticles regulate stretchability, thus enabling radiative cooling, evaporative cooling, and sorption-induced heat release within one system. This all-in-one materials design yields high solar reflectance (0.87) and thermal emittance (0.94), alongside rapid, autonomous water uptake and release driven by environmental stimuli. Consequently, the soft photonic interface achieves up to 7.1 °C subambient cooling during the daytime and a 5.8 °C nighttime temperature increase via continuous hygroscopic latent heat release, effectively mitigating diurnal overcooling without external energy input. This work establishes a soft-matter strategy for autonomous and bidirectional thermal regulation across deformable and complex surfaces.