Self-Modifying Nanointerface Driving Ultrahigh Bidirectional Thermal Conductivity Boron Nitride-Based Composite Flexible Films

While boron nitride (BN) is widely recognized as the most promising thermally conductive filler for rapidly developing high-power electronic devices due to its excellent thermal conductivity and dielectric properties, a great challenge is the poor vertical thermal conductivity when embedded in composites owing to the poor interfacial interaction causing severe phonon scattering. Here, we report a novel surface modification strategy called the self-modified nanointerface using BN nanocrystals (BNNCs) to efficiently link the interface between BN and the polymer matrix. Combining with ice-press assembly method, an only 25 wt% BN- embedded composite film can not only possess an in-plane thermal conductivity of 20.3 W m(-1) K-1 but also, more importantly, achieve a through-plane thermal conductivity as high as 21.3 W m(-1) K-1, which is more than twice the reported maximum due to the ideal phonon spectrum matching between BNNCs and BN fillers, the strong interaction between the self-modified fillers and polymer matrix, as well as ladder-structured BN skeleton. The excellent thermal conductivity has been verified by theoretical calculations and the heat dissipation of a CPU. This study provides an innovative design principle to tailor composite interfaces and opens up a new path to develop high-performance composites.

Automated summary

This study presents a novel surface modification strategy using BN nanocrystals to enhance the vertical thermal conductivity of BN-embedded composites. The self-modified nanointerface between BN and the polymer matrix improves the phonon scattering issue and achieves a significantly higher through-plane thermal conductivity. The excellent thermal conductivity has been verified by theoretical calculations and experimental tests, making it a promising approach to develop high-performance composites.