"Brick-mud" Porous Impregnated-segregated Polymer Composites with Excellent Electrical Insulation, High Thermal Conductivity, and Good Electromagnetic Interference Shielding

Abstract

The advancement of 5G communication systems and modern electronic devices has driven the demand for advanced polymer composites with multifunctional capabilities, including electromagnetic interference (EMI) shielding, thermal conductivity, electrical insulation, and mechanical robustness. However, achieving an optimal combination of these properties in a single polymeric material remains challenging. Here, a novel "brick-mud" porous impregnated-segregated structure was developed to address these challenges. This structure consists of polylactic acid/multi-wall carbon nanotubes (PLA/CNTs) microspheres as the "brick" phase and polybutylene succinate/boron nitride (PBS/BN) as the "mud" phase. The interconnected porous PLA/CNTs microspheres were prepared via an emulsion method, which allowed effective infiltration by the PBS/BN matrix during melt blending, resulting in a robust interface. The ratio of "mud" to "brick" was systematically varied, facilitating regulation of the balance between the different multifunctional properties. The resulting composites demonstrated excellent performance, with EMI shielding effectiveness up to ∼41.1 dB, thermal conductivity up to ∼1.37 W·m⁻¹·K⁻¹, volume resistivity exceeding 10¹⁵ Ω·cm, and mechanical strength as high as ∼54.2 MPa, depending on the composition. Such performance characteristics make these composites particularly suitable for use as casings for 5G communication equipment, where efficient thermal management, EMI shielding, and structural durability are critical.