Bioinspired Passive Cooling Hydrogel for Visualizing Hygroscopicity and Desorption Process

Self-hygroscopic hydrogels, characterized by high evaporation enthalpy, cooling efficiency, and self-regulating properties, have garnered significant attention. However, most current research focuses on enhancing the hygroscopic and desorption performance, often overlooking the importance of monitoring the self-regulation process, which limits its further application. Advanced visualization technologies, such as in situ electrical impedance tomography, low-field nuclear magnetic resonance, and hyperspectral imaging, offer potential insights into this behavior, yet they often require additional devices, incur high costs, and involve complex sample preparation processes. Therefore, drawing inspiration from nature, humidity-color-sensitive hydrogels (HCSHs) strategy is proposed for visualized cooling. Benefiting from the strong polar responsiveness of the aggregation-induced emission (AIE) molecules, the hydrogel's fluorescence significantly changes with varying interior water content, thereby its self-regulation process is monitored easily. Further, the obtained hydrogel could be applied in the electronic device cooling owing to the polymer skeletons’ high swelling ratio, strong adhesion, and excellent self-hygroscopic properties. This strategy overcomes current limitations in the visual technology of self-hygroscopic materials and provides new insights into intelligent thermal management for electronic devices.