High-performance nitride boron reinforced composites by vertical graphene interfacial modification

Filling boron nitride nanoribbons (BNNRs) into polymers can achieve a significant increase in the thermal conductivity of polymers at a low filler loading as compared to the commonly used flaky and fibrous ceramic nanofillers. However, due to the electrically insulating nature of BNNRs and the weak BNNR/polymer interfacial bonding strength, the resulting polymer composites have almost no electromagnetic interference (EMI) shielding capability and low mechanical strength, limiting their applications in areas where EMI shielding protection and load bearing capacity are required. The introduction of electrically conductive nanomaterials at the BNNR/polymer interfaces is an effective strategy to simultaneously improve the interfacial stress transfer efficiency and the EMI shielding effectiveness (SE). Herein, vertical graphene (VG) with rich structural defects is grown in situ onto the surfaces of BNNRs, followed by composition with polydimethylsiloxane (PDMS). Due to the excellent electrical conductivity and charge polarization capability of VG, the resulting VG-BNNR/PDMS composites exhibit a high broadband EMI SE of 64.9 dB with a thickness of 2 mm, outperforming the reported polymer composites containing carbon and/or ceramic nanofillers at similar thicknesses. By tuning the growth time of VG, a high tensile strength of 11.4 MPa and outstanding thermal conductivity of 14.5 W·m⁻¹·K⁻¹ are also observed for the resulting composites, which are 516 % and 77 % higher than that of BNNR/PDMS composites, respectively. This work demonstrates that VG is an effective interfacial nanomaterial capable of significantly improving the load-bearing capacity and other functional properties of ceramic nanofiller/polymer composites.