Ag Nanoparticle/Ag Nanowire/PVDF Composite Nanofiber Membranes for Outdoor Heating

The development of outdoor heating materials combining wearing comfort with energy saving and environmental sustainability has attracted significant research attention. In this study, high-purity silver nanomaterials of two different dimensions─zero-dimensional Ag Nanoparticles (AgNPs) with an average diameter of 110.82 nm and one-dimensional Ag Nanowires (AgNWs) with average dimensions of 32.68 μm in length and 46.2 nm in diameter─were successfully synthesized by precisely adjusting the NaCl-to-NaBr control agent ratio. Subsequently, PVDF/AgNPs/AgNWs composite nanofiber membranes were fabricated via electrospinning. The results showed that AgNWs primarily contributed to enhancing the mechanical properties of the nanofiber membranes, whereas AgNPs improved the thermal insulation performance, reducing the thermal conductivity to 17.5 mW·m–1·K–1. The final PVDF/AgNPs/AgNWs composite membrane exhibited an exceptional photothermal conversion ability, reaching a temperature increase of ∼6 °C compared to the other two PVDF composite nanofiber membranes, and 15 °C relative to the pure PVDF nanofiber membrane, after 5 min of light irradiation at 0.1 W·cm–2. Meanwhile, it also demonstrated satisfactory air permeability (64 mm·s–1), desirable hydrophobicity (water contact angle of 137°), and moderate thermal insulation (thermal conductivity of 18.3 mW·m–1·K–1). These findings suggest that the PVDF/AgNPs/AgNWs composite membrane holds potential as a high-performance outdoor heating material, especially in cold and humid regions.