A Moisture-Wicking Hierarchical Metafabric Based on Waterborne Polyurethane for Passive Daytime Radiative Cooling

The radiative cooling technology in personal thermal management (PTM) offers a favorable technical means for energy savings and heat dissipation. However, the PTM technology is facing the challenge of integrating radiative cooling performance, wearing comfort, and scalable production. Addressing these challenges, this study proposes a hierarchical radiative cooling metafabric that can be manufactured in industry. Through the synergistic effect of the gradient pore structure (7–8 μm scattering cavity/60 μm capillary channel) and WPU/BaSO4 composite system, 91.8% solar reflectivity and 95.2% atmospheric window emissivity are achieved. The hierarchical structure supports dry/wet dual-mode cooling: radiative cooling provides a 12.8 °C temperature drop in dry environments, and moisture-wicking combined with evaporative cooling provides a 21.3 °C temperature drop in sweaty environments. The actual outdoor human temperature measurements show that the skin temperature covered by metafabric is 3 °C lower than that covered by cotton fabric. In addition, the potential of metafabric for color, multiscenario application, and energy savings are also explored. The hierarchical metafabric introduces new possibilities in the rational design of next-generation PTM textiles and development.