Nacre-mimetic elastomer composites with synergistic alignments of boron nitride/graphene oxide towards high through-plane thermal conductivity

Thermal-conductive yet electrical-insulating polymer composites are in urgent demand in modern microelectronics for efficient heat dissipation. However, the reported through-plane thermal conductivity of polymer composites under low filler loadings (<10 vol%) is dissatisfactory, due to undesirable heat transfer pathways and high interfacial thermal resistance. Herein, 3D lamellar‑structured fluorinated boron nitride nanosheets (F-BNNS)/graphene oxide (GO) skeleton prepared by bidirectional freezing assembly ensures the directional motion of heat flow, in which GO bridges adjacent F-BNNS for reducing thermal resistance via hydrogen bond of H-F and van der Waals interaction. After vacuum-infiltrating polydimethylsiloxane (PDMS), the 9.5 vol% F-BNNS/GO/PDMS presents fascinating characteristics: a high through-plane thermal conductivity of 3.28 W·m−1·K−1 and an excellent tensile strength of 3.19 MPa, with the enhancements of 1829% and 118% respectively compared to pure PDMS; besides, superior dimensional stability and electrical insulation were obtained, with thermal expansion coefficient of 79 ppm/K and volume resistivity of 2.45 × 1012 Ω·cm.