Micro-extrusion foaming fabricating porous polyester elastomeric fiber for using in radiative cooling fabrics

Climate change has unleashed relentless global heatwaves, posing grave threats to the physical and mental well-being of outdoor laborers and the smooth functioning of society. Porous polymeric fibers exhibit promising potential in personal thermal management for wearable fabrics. Nevertheless, the absence of an environmentally friendly, cost-effective, and efficient method for producing the desired porous fibers remains a formidable challenge. Here, we introduce a pioneering micro-extrusion foaming technique for crafting elastic porous fibers endowed with dense longitudinally oriented cell morphologies, remarkable porosity of 69 % and elongation of 668 %. The technique enabled the continuous production of porous fibers exceeding 3000 m in length in a single operation, with fiber diameters controlled to approximately 0.25–0.55 mm. Fabrics woven from the elastic porous fiber offered a soft touch, proficiently reflecting more than 90.0 % of incident solar radiation and emitting 91.9 % of absorbed heat radiation, thereby achieving a theoretical radiant cooling power of 111.46 W/m² on sunlit days. Leveraging the controllable and scalable attributes of micro-extrusion foaming, the porous fiber is primed for practical deployment and expansion into diverse wearable applications.