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.

虽然氮化硼（BN）因其优异的导热性和介电性能而被广泛认为是快速发展的高功率电子器件中最有前途的导热填料，但由于其嵌入复合材料中时的巨大挑战，垂直导热性较差。不良的界面相互作用导致严重的声子散射。在这里，我们报告了一种新颖的表面改性策略，称为“自改性纳米界面”，使用氮化硼纳米晶体（BNNC）来有效连接氮化硼和聚合物基体之间的界面。^{结合冰压组装方法，仅25 wt% BN嵌入的复合薄膜不仅可以具有20.3 W m -1}  K ^-1的面内导热系数，更重要的是，还可以实现穿面导热系数高达 21.3 W m ⁻¹  K ⁻¹，这是报道的最大值的两倍多，这归因于 BNNC 和 BN 填料之间理想的声子谱匹配、自改性填料与聚合物基体之间的强相互作用以及梯形结构-结构化BN骨架。其优异的导热性能已通过理论计算和CPU散热得到验证。这项研究提供了定制复合材料界面的创新设计原理，并开辟了开发高性能复合材料的新途径。