Hierarchically Porous Super-Hygroscopic Hydrogel with Wide Humidity Regulation Capability for Enhancing Thermal Comfort in Protective Clothing

The impermeable structure of personal protective clothing not only safeguards the wearer in hazardous environments but also traps heat and moisture, which can lead to heat stress. Moisture absorption can regulate humidity inside clothing to promote sweat evaporation and skin cooling, thereby alleviating discomfort. Herein, we developed a hierarchically porous superhygroscopic γ-PGA/UiO-66-NH 2 /LiCl composite hydrogel for effective moisture management. The material features a hierarchically porous structure combining macropores of γ-PGA and micropores of UiO-66-NH 2 that enables efficient water capture across a wide humidity range. Synergistic effects between the porosity of MOFs and the anchoring action of γ-PGA allow the composite material to rapidly absorb water under a low humidity of 30% RH (reaching 20.08 mg/g within 12 min), significantly outperforming the pure γ-PGA hydrogel. Under a high humidity of 90% RH, the dominant role of LiCl enables exceptional water adsorption capacity (1909.86 mg/g at 200 min). The hydrogel achieves ultrahigh saturation moisture uptake of 0.36 g/g and 7.61 g/g under 30% and 90% RH, respectively. The structural stability is attributed to multiple intermolecular interactions including hydrogen bonding and coordination, which collectively contribute to a high tensile strength of 3.81 MPa. After 30 adsorption–desorption cycles and 45 tensile tests, the hydrogel maintains excellent cyclic durability and exceptional mechanical properties. When applied to protective clothing, the composite hydrogel reduces internal relative humidity significantly from 90.1% to 60.7% under moderate sweating and decreases evaporative resistance to just 29.3% of the original value, thereby enhancing the evaporation of sweat from the human body and greatly alleviating heat stress. This work not only focuses on the promising potential of the composite hydrogel in moisture absorption but also provides an effective strategy for improving thermal comfort in personal protective equipment.