Polyetherimide Composites Doped with Boron Nitride Nanosheets Were Prepared by Embedded Series Strategy to Improve the Thermal Management Capability

Abstract

Due to the continuous development of semiconductor technology and the rapid increase in power density of modern electronic devices, there is an urgent need for a thermal interface material (TIM) with ultra-high heat dissipation capacity and excellent electrical insulation. Here, we report a new embedded series strategy for preparing thermal interface materials. Ultra-thin boron nitride nanosheets (BNNS) were efficiently prepared by suitable sonication-assisted liquid phase exfoliation method, and these BNNS were continuously and neatly embedded in oriented fibers by electrospinning to form an ordered series structure of BNNS. Then these composite fibers are stacked in multiple layers along the orientation direction. Finally, the stacked composite fibers are pressed into film by suitable hot pressing conditions. This strategy not only effectively reduces the interfacial defects in the composite, but also completely retains the morphologies of BNNS neatly in series along the fiber direction. This strategy can provide a high-speed channel for phonon transfer in the composite, thereby directionally improving the heat transfer capacity of the composite. The composites prepared by the embedded series strategy have higher thermal anisotropy (λ=/λ⊥ = 7.16) and in-plane thermal conductivity (3.08 W/(m·K), BNNS Loading: 30 wt%), and also exhibit better electrical insulation (8.16×1015 Ω·cm) than those prepared by solution coating and hot pressing. By capturing the surface temperature changes of the composites prepared by the three strategies in infrared thermal image and simulation model, it is proved that the form of directional heat transfer can make the composite have excellent thermal management capability.

Keywords: Boron nitride nanosheets, electrostatic spinning, embedded series strategy, Composite, In-plane heat conduction, directional heat transfer