Silver Nanoparticle-Enhanced Three-Dimensional Boron Nitride/Reduced Graphene Oxide Skeletons for Improving Thermal Conductivity of Polymer Composites

Abstract

The thermally conductive properties of polymer composites are hugely constrained by discontinuous filler networks and high thermal contact resistances in filler/filler interfaces. Herein, a silver nanoparticle-decorated boron nitride hybrid (BN@AgNPs) is fabricated via in situ reduction of Ag+. Subsequently, the AgNP-enhanced three-dimensional BN/reduced graphene oxide (3D-BN/rGO) skeleton with continuous structures possessing “point-plane” connections is prepared via hydrothermally treating the aqueous slurry containing BN@AgNPs and GO followed by freeze-drying. It is established that rGO serves as a scaffold to assemble BN@AgNPs into 3D structures. Notably, the AgNP-enhanced 3D-BN/rGO skeleton makes the polydimethylsiloxane (PDMS) composite exhibit a high thermal conductivity of 2.34 W m–1 K–1 at a low filler loading of 23.8 wt %, which is 41.8 and 207.9% higher than that of the PDMS composite incorporated with the original 3D-BN/rGO skeleton and BN flakes at the same loading, respectively. Meanwhile, the composite also exhibits a high volume resistance of 6.9 × 1013 Ω cm–1. Thermal resistance analysis demonstrates that assembling BN flakes into 3D skeletons makes phonon transfer along BN flakes rather than BN/PDMS interfaces with larger resistances, and the introduction of AgNPs depresses the phonon scattering in BN/BN interfaces. Finite element simulation further reveals that the AgNPs on BN planes and BN edges elevate the heat transfer in BN planes and BN/BN interfaces, respectively. Our work provides a promising approach for fabricating thermally conductive and electrically insulating polymer composites utilized in electronics.