SiO ₂ /Boron Nitride Network for Enhancing the Thermal Conductivity and Solar Reflectance of Thermoplastic Polyurethane Nanofibers

Outdoor electronic devices face severe thermal challenges because conventional polymer enclosures trap internal waste heat, a problem significantly exacerbated by solar irradiation. To address this, we developed a thermoplastic polyurethane (TPU)/SiO2/boron nitride (BN) nanofiber with synergistic thermal conductivity regulation and radiative cooling. SiO2 nanoparticles were incorporated into TPU via electrospinning to enhance solar reflection, achieving a 5 °C temperature reduction under simulated sunlight. BN nanosheets were then decorated on TPU/SiO2 nanofibers, followed by hot-pressing to form interconnected thermal conduction networks, increasing the in-plane thermal conductivity to 6 W m–1 K–1. The nanofiber exhibited excellent flexibility, hydrophobicity, and superior cooling performance─lowering LED temperatures by up to 6 °C outdoors compared to TPU nanofibers, cotton fabric, and PDMS film. It also maintained stable performance over 1000 heating–cooling cycles. This nanofiber offers a promising solution for thermal management of high-power-density devices.