Liquid Metal-Reinforced Epoxy Nanocomposite with Enhanced Mechanical Properties and Superior Electrical and Thermal Conductivity

The rapid development of aerospace, automotive, and advanced electronics industries has necessitated the development of multifunctional materials featuring high flexural strength, fracture toughness, and superior electrical and thermal conductivity. Incorporating bio-inspired conductive scaffolds into tough polymer matrices represents a promising strategy to address these comprehensive performance requirements. However, existing bulk nanocomposites typically exhibit limited electrical and thermal conductivity, insufficient for increasingly demanding technological applications. In this study, electron and phonon transport within an epoxy (EP) matrix are significantly enhanced by introducing a continuous liquid metal (LM) phase into a reduced graphene oxide/polyimide scaffold (PrGO). The resulting EP/PrGOLM nanocomposite exhibits outstanding flexural strength (144.9 MPa) and fracture toughness (4.55 MPa m^1/2), combined with ultrahigh electrical conductivity (53379 S m⁻¹) and thermal conductivity (18.4 W m⁻¹ K⁻¹). Due to this exceptional combination of properties, the EP/PrGOLM nanocomposite achieves remarkable average electromagnetic interference (EMI) shielding effectiveness (SE) over X-band up to 78 dB at a small thickness of 0.1 mm, while its specific SE (780 dB mm⁻¹) surpasses current records reported for bulk nanocomposites. These results clearly demonstrate that the EP/PrGOLM nanocomposite holds substantial potential for advanced applications in aerospace, automotive, and next-generation electronic devices.