Stereocomplexation-Enhanced Biomimetic Janus Poly(Lactic Acid) Metafabric for High-Power Passive Personal Cooling

The development of biodegradable radiative cooling textiles that simultaneously deliver high solar reflectance, efficient sweat management, and long-term durability remains challenging. Here, we report a hierarchical Janus poly(lactic acid) (PLA) metafabric (J-PLA) enabled by molecular stereocomplexation and a plant-transpiration-inspired dual-gradient architecture. Stereocomplexation between poly(l-lactic acid) and poly(d-lactic acid) chains fundamentally enhanced the mechanical robustness and infrared vibrational intensity of the PLA matrix. Concurrently, a biomimetic dual-gradient structure, replicating the transpiration network of vascular plants, was constructed by electrospinning a hydrophilic stereocomplexed PLA/SiO₂ nanofiber layer onto a hydrophobic PLA microfiber substrate. This unique architecture enabled ultrafast directional water transport (<21 s) and superior spectral selectivity, achieving a solar reflectance of 94.2% and a mid-infrared emittance of 93.3%. Under outdoor direct sunlight (dry condition), J-PLA achieved a maximum temperature reduction of 12.1 °C relative to bare skin and 7.2 °C relative to cotton. Under simulated sweating, directional transport and evaporation further enhance cooling, providing an additional 7.6 °C reduction at a sweat rate of 0.5 mL h^-1. This work provides a novel and sustainable design paradigm for next-generation, high-performance personal thermal management textiles.