Flexible solid-liquid nanocomposite with high surface resistivity for effective electromagnetic interference shielding and heat dissipation.

The miniaturization of electronics and increased power density pose significant challenges, including short circuits, electromagnetic interference (EMI) and heat accumulation. Developing electrically insulative materials that integrate EMI shielding and heat dissipation capabilities offers an effective solution. However, developing such materials is challenging due to the inherent conflict between creating electrically and thermally continuous pathways for EMI shielding and heat dissipation while maintaining electrical insulation. Herein, we sequentially integrated boron nitride nanosheet-bridging-liquid metal (BLM) and MXene-bridging-liquid metal (MLM) solid-liquid bi-continuous networks into poly-p-phenylene benzobisoxazole (PBO) nanofiber matrices. This yielded a sandwich-structured nanocomposite (S-PBLM/MLM) that demonstrates high electrical insulation (volume resistivity of 1.9 × 10¹³ Ω cm, breakdown voltage of 139 kV mm^-1), promising EMI shielding performance (68.2 dB at a thickness of 25 μm), and excellent in-plane thermal conductivity (50.3 W m^-1 K^-1). Meanwhile the S-PBLM/MLM nanocomposite demonstrates stable EMI shielding performance even after enduring harsh conditions, including mechanical wear, high humidity storage, ultrasonication treatment, extreme temperatures, thermal shock and direct burning. Furthermore, the nanocomposite displays high mechanical strength (tensile strength: 252.6 MPa, toughness: 8.8 MJ m^-3). This nanocomposite has significant potential in the fields of modern electronics, aerospace, and defense.