Plasma‐Modified Boron Nitride Nanosheets for High‐Performance Aramid‐Based Dielectric Films with Enhanced Multifunctionality

Aramid paper, due to its lightweight structure, mechanical strength, and excellent dielectric performance, is widely employed in insulation systems of electronic devices and high-voltage equipment. However, its inherently poor thermal conductivity (λ) restricts its applicability in modern high-power systems with demanding thermal management needs. Additionally, conventional blending approaches often yield poor filler-matrix interfaces, which severely limit the enhancement of λ and simultaneously deteriorate other properties. Herein, a plasma-assisted amino functionalization approach is reported for boron nitride nanosheets to reinforce its interfacial affinity with 1D aramid nanofibers (ANF). Together with Silk Fibroin (SK), serving as a flexible molecular binder, a biomimetic nacre-inspired architecture is achieved through a self-assembly process. The synergistic effect of strong interfacial interactions and a 3D hydrogen bonding network endows the composite films with outstanding thermal conductivity of 13.89 Wm^-1K^-1, excellent tensile strength of 307.08 MPa, as well as superior thermal resistance and long-term operational stability. Moreover, the highly ordered microstructure results in an ultrahigh breakdown strength (up to 430 kVmm^-1) and a low dielectric loss. The findings of this study provide a rational design strategy for multifunctional polymer-based dielectric materials aimed at next-generation high-power electronic devices.