Colored BN-Based Composite Film with Superior Spectrally Selective, Thermal Conductivity, and Antibacterial Properties for All-Weather Thermal Management in Electrical Devices.

Developing advanced polymer-based composite materials integrating zero-energy thermal management and aesthetic experience can achieve lightweight and compact thermal management for electrical devices. For this goal, we propose a colored spectrally selective film (SSF) combining the plate hexagonal boron nitride with waterborne polyurethane. After a facile and scalable mechanical stirring method, the resulting composite colored SSF exhibits a favorable optical performance, which maintains a thermal emittance (ε) of ∼92.6%, while possessing a high thermal conductivity of 0.834 W·m-1·K-1. Benefiting from the synergy of the above two aspects, our colored SSFs can reduce temperatures by up to ∼15 °C compared to the bare heater with the input power of 2.75 kW·m-2. Additionally, the white SSF with an exceptional reflectance (r) of 92.7% in the solar spectrum can achieve an average temperature drop of 16.07 °C when subjected to an extra solar irradiation of 1 kW·m-2, with an estimated cooling power of 100.98 W·m-2. More attractively, our SSF exhibits an excellent antimicrobial rate of 99.99%, enabling it to simultaneously achieve thermal management and sterilization protection for interactive smart devices. All these competitive performances render our colored SSFs a potentially promising candidate for all-weather thermal management in electrical devices.