In-situ exfoliation of hexagonal boron nitride during the forced flow of highly elastic polylactide to fabricate electrospun fibrous film with high thermal conductivity and low dielectric loss

Abstract

Boron nitride nanosheets (BNNS) have promising applications in thermal management materials, due to their high thermal conductivity and low dielectric loss. However, it is still challenging to fabricate BNNS with large lateral size and structural integrity via solvent-free methods. Here, we report a novel processing method for in-situ exfoliation of hexagonal boron nitride (h-BN) to fabricate BNNS with an average lateral size of 1.45 μm, average thickness of 4.88 nm and few lattice defects during the forced flow of polylactide (PLA) in a highly elastic state. We further fabricate flexible and bio-degradable PLA/BNNS electrospun fibrous film for electronic devices to replace petroleum-based composites. The PLA/BNNS fibrous film exhibits an in-plane thermal conductivity of 4.9 W/(m·K) at the BNNS loading of 20 wt%. Moreover, the fibrous film also has a low dielectric loss (0.007 at 1 kHz) and good electrical insulation. The in-situ exfoliation strategy is simple, economical and environmentally friendly, providing an effective route to design thermal management materials with high thermal conductivity and low dielectric loss in the future of electronic devices.