Bioinspired 3D Helical Nanofiber Metafabrics for Concurrent Thermal Management and Particulate Protection

Nonwoven polymer fibrous materials have been widely adopted in passive radiative cooling due to their controllable subwavelength dimensions that relate to the visible to mid-infrared light regulation. However, existing radiative cooling fabrics, whether electrospun 2D nonwovens made of straight nanofibers or multilayer fabrics with functional coatings, sacrifice the crucial textile function of air-moisture permeability. Here, we explore the manufacturing and optical property engineering of 3D helical nanofibers for efficient radiative cooling alongside highly permeable air purification. Inspired by biological tendrils, cellulose acetate (CA) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) are cospun via air-blown electrospinning, where their mechanical properties mismatch combined with electrostatic airflow perturbation drive the formation of helical fibers. The resulting helical nanofiber metafabric (HNMF) with its hierarchically porous nanohelix architecture and CA/PVDF-HFP molecular backbones, achieves ∼96% solar reflectance and ∼91% emission within the atmospheric transmission window. This enables effective radiative cooling while simultaneously removing >99.9% of PM_0.3 particles at a low-pressure drop (52.8 Pa). Outdoor evaluations and building energy simulation confirm the practical applicability of HNMF for use as protective curtain and masks in addressing environmental thermal stress and particulate matter exposure, highlighting its potential as a multifunctional and scalable material platform for wearable personal protection and energy-efficient building solutions.