BiofriendlyHygroscopic Polyacrylamide Composite HydrogelFilm for Efficient Human Body Thermal Management in High-TemperatureEnvironment

High temperature and humidity conditions can lead to metabolic disorders in the human body, equipment corrosion, and bacterial growth. Therefore, the development of efficient, reusable, and biofriendly dehumidifying materials is urgently needed. For this purpose, we developed a humidity-sensitive polyacrylamide composite hydrogel film aimed at effectively regulating skin surface temperature, which enhanced comfort and thermal safety in high-temperature environments. Comprising poly(vinyl alcohol), poly(ethylene glycol), and the loaded hygroscopic salt (LiCl), the three-dimensional network-structured polyacrylamide composite hydrogel facilitated rapid evaporation of absorbed moisture to dissipate excess heat. Herein, the phase change material polyethylene glycol was incorporated as a thermal storage medium for efficient heat regulation and release. This composite hydrogel film could achieve moisture absorption of about 722.1 g m^–2 at an external temperature of 50 °C and 90% RH. After conducting 15 absorption–desorption experiments and 20 cyclic tensile tests, the hydrogel demonstrated remarkable stability and reusability. Furthermore, the temperature of the arm covered with the polyacrylamide composite hydrogel film can be reduced by 2.2 °C when it is utilized in direct sunlight. Due to low-cost, straightforward manufacturing processes, and reusability, this composite hydrogel film offers a promising strategy for various applications confronting significant thermal discomfort and stress.