Nanoporous Boron Nitride Aerogel Film and Its Smart Composite with Phase Change Materials

With the advent of the 5G era, electronic systems have become more and more powerful, miniaturized, integrated ,and intelligent. The thermal management of electronic systems requires more efficiency and multiple functions for their practical applications, especially for the portable 5G electronic devices of the future, as the undesired heat can cause thermal discomfort or even thermal injury to people who use these electronic devices. Herein, two thermal management strategies based on boron nitride (BN) aerogel films have been proposed and demonstrated for portable devices. First, a flexible BN aerogel film with high porosity (>96%), large specific surface area (up to 982 m² g^-1), and controllable thickness (in the range from 50 to 200 μm) was fabricated via molecular precursor assembly, sublimation drying, and pyrolysis reaction in sequence. The resulting BN aerogel film individuals, serving as a thermal insulation protecting layer in portable electronics, can significantly reduce heat transfer from electronics to skin. Second, BN phase change composite films, made by dipping BN aerogel films into the melts of the organic phase change materials (e.g., paraffin), can effectively cool the portable electronics as the organic phase change materials filled in the aerogel matrix can serve as a smart thermal-regulator to absorb the undesired heat via solid-liquid phase transition. These two typical strategies of the flexible BN aerogel film-directed thermal management could assist in efforts to miniaturize, integrate, and intelligentialize portable 5G electronic devices in the future.