Knittable ultra-high molecular weight polyethylene microporous fibers for all-day personal passive radiative cooling in outdoors

Polyethylene (PE) has been recognized as a basic material with great potential for personal thermal management garments, expected to realize industrialization at a low cost. However, post-treatment or functional additives tend to be used to improve the wearability properties and cooling performance of PE textiles, which not only increases the production expense but also is unfavorable to recycling. Here, we fabricated an ultra-high molecular weight polyethylene (UPE) microporous fiber with high porosity (∼70.2 %) and nano pores (0.56 ± 0.43 μm) by gel spinning and multistage extraction. Without any modification, the woven fabrics can exhibit a low thermal conductivity (31–37 mW m−1 K−1), high mid-infrared transmittance (85.7 %) and solar reflectivity (96 %). The UPE fabric was demonstrated to reduce the simulated skin temperature by average 5.2 °C under direct sunshine of 800 W m−2 and allowed for a subambient temperature close to bare skin at night, realizing personal cooling all day in outdoors. Attributing to the weaving structure of the UPE fabric, its wearability and durability are superior to traditional textiles, such as cotton and Tyvek, and it can meet the requirements of most people for wearing comfort. UPE microporous fibers provide a possible opportunity for large-scale production and practical application of radiation cooling clothing.