Fabrication of artificial nacre-like hexagonal boron nitride/lignocellulosic fiber composites with high thermal conductivity

Abstract

The low thermal expansion coefficient, low dielectric constant, high thermal conductivity, high electrical resistivity, and excellent thermal stability of hexagonal boron nitride (hBN) make it an ideal filler for insulating and thermally conductive composite films. Its use has been suggested in insulating packaging systems to solve the heat dissipation problems in modern electronic equipment. Here, a novel strategy was proposed to construct superior thermally conductive networks via the vacuum-assisted filtration of hydroxyl-modified hexagonal boron nitride (BN-OH) and lignocellulosic fiber (LCF). The π–π interactions between the benzene ring of LCF and the hBN plane assist in the dispersal of BN-OH in aqueous solution. The abundance of functional groups such as hydroxyl and phenolic hydroxyl groups in the LCF structure allow for hydrogen bonding with the hydroxyl groups on the BN-OH surface, increasing interfacial interactions between BN-OH and LCF and reducing interfacial thermal resistance. In addition, the long-range one-dimensional structure of LCF can assist in the formation of a self-supporting, high-thermal-conductivity film with a high content of BN-OH. The through-plane thermal conductivity of BN-OH/LCF reached 5.34 W/(m⋅K) at 90 wt.% BN loading. This work provides inspiration for the green preparation of hBN thermally conductive composite films with high filler loadings.