Highly thermally conductive, ductile biomimetic boron nitride/aramid nanofiber composite film

Combining a large volume of boron nitride platelets with a little polymer to fabricate ductile, thermally conductive composite materials for the thermal management of flexible electronic devices is a challenge. Herein, we imitate the hierarchical layered architecture of mollusk nacre to design high-loading boron nitride composite film. Boron nitride/aramid nanofiber composite films are prepared by a sol-gel-film transformation approach and show nacre-like hierarchical layered composite structure. High-strength aramid nanofibers form a three-dimensional framework as matrix, which hosts 40–70 wt% oriented BN platelets. Thanks to the high interconnectivity of aramid nanofiber in the three-dimensional framework, the composite films have large ductility, up to 18.3–49.4%. Meanwhile, the composite films have high thermal conductivity (47.4–122.5 W m−1 K−1) because high-loading boron nitride platelets form a percolative, oriented heat conduction path. Moreover, the outstanding ductility and thermal conductivity are integrated with high volume resistivity (1014–1016 Ω cm) and thermal decomposition temperature (515 °C), enabling the structured boron nitride/aramid nanofiber composite films to be promising as flexible substrate for cooling electronic components.