Constructing Fibrillated Skeleton with Highly Aligned Boron Nitride Nanosheets Confined in Alumina Fiber via Electrospinning and Sintering for Thermally Conductive Composite

Abstract Various fillers and methods have been utilized to enhance the thermal conductivity (TC) of polymer-based electronic packaging materials, however, the enhancement was limited by disconnected pathway for phonon transferring. Herein, a novel fibrillated hybrid skeleton (f-AO@BNNS skeleton) was fabricated by dispersing boron nitride nanosheet (BNNS) into alumina (AO) sol, electrospinning and sintering, where long-range phonon transferring highway was successfully constructed by both macroscopically interconnected fiber and microscopically oriented and overlapped BNNSs confined in nanofiber. Besides, crystal AO and atomic-level bonding were acquired on BNNS-AO interface by sintering, largely decreasing interface thermal resistance inside skeletons. Prepared polybenzoxazine/f-AO@BNNS composites exhibited the highest TC of 3.24 Wm−1 K−1 at a skeleton loading of 6.9 vol%. The higher TC was achieved at lower filler content when compared with other reported skeletons, demonstrating the superiority of f-AO@BNNS skeleton. This work provides a new strategy of preparing fibrillated hybrid skeleton for high thermally conductive composites.