Fluorinated interface engineering targeting high-performance multifunctional composites of BN/aramid nanofibers

Aramid nanofibers (ANFs)-based composites have attracted considerable interest in electronic and electrical engineering due to their exceptional thermal stability, high strength, and superior insulating properties. However, the performance of ANFs-based composites is severely confined by interfacial issues. Accordingly, a novel strategy of fluorinated interface engineering is proposed herein, by which the fillers are grafted by the fluorine-containing functional groups. The introduction of interfacial fluorination yields a dense and compact composite structure which stems from the improved compatibility at the matrix-filler interfaces. The tensile strength and thermal conductivity are increased by 30% and 50%, respectively. Additionally, the band structure variation is observed in the fluorinated BNNs, where the electron trap states are formed at the interface. With the deepened deep trap depth and increased density, the breakdown strength is enhanced by 50%. The breakdown phase field simulations also indicate the high discharge energy consumption by the fluorination effect.