Bioinspired engineering of breathable poly(lactic acid) metafabric with high-performance radiative cooling and...

Passive daytime radiant cooling (PDRC) represents a sustainable, energy-free technology for personal thermal management (PTM). However, conventional polymer membranes frequently exhibit insufficient solar reflectance and poor breathability. Herein, inspired by dictyophora, we propose a biomimetic gradient pore engineering (BGPE) strategy. Specifically, this strategy utilized a multicomponent phase separation electrospinning technique to generate nanopores at the surface of poly(lactic acid) (PLA)microfibers. The nanopores, in conjunction with the micropores that form between the fibers, collectively established a distinctive gradient pore architecture. Via stepwise electrospray, the well-defined UiO-66 MOF nanocrystals were preferentially anchored on PLA fibers for optically optimized crystals. Certainly, this approach successfully constructed a PLA-based metafabric with gradient pore structure and high-performance radiative cooling. In this work, the bioinspired hierarchies and enhanced photo-functionalization of the BGPE-PLA metafabric demonstrates a reflectivity of 94.1% (0.3-2.5 μm) and a mid-infrared (MIR) emissivity of 95.4% (8-13 μm). In outdoor application scenarios, the metafabric exhibit an average temperature difference of 6.8 °C and an excellent net cooling power of 106.7 W m^-2. Concurrently, the metafabric exhibits notable hydrophobicity and excellent self-cleaning due to the synergistic effect of its surface roughness and low surface energy. Furthermore, the metafabric exhibits breathability (41.2 mm s^-1), excellent moisture permeability (132.3 g h^-1 m^-2) and favorable flexibility, in great need for desired wearing comfort and long-term stability. This work presents a multifunctional biodegradable fabric with high potential for PDRC materials and PTM applications.