Insulating yet terahertz-shielding Epoxy/MXene composites for impact-resistant electronic encapsulation

The development of electronic encapsulation materials for munitions requires a unique combination of high impact resistance, effective electromagnetic interference (EMI) shielding, and reliable electrical insulation. Traditional epoxy resins often fall short in mitigating extreme mechanical loads and complex electromagnetic threats simultaneously. This study addresses this challenge by fabricating epoxy (Ep) composites incorporated with two-dimensional Ti 3 C 2 T x MXene nanosheets (0.5∼4 wt.%) as multifunctional fillers. The Ep/MXene composites were systematically evaluated for their mechanical properties, impact resistance, and electromagnetic shielding effectiveness across GHz and THz bands. Results indicate that an optimal MXene content of 2 wt.% yields a superior balance of properties, achieving a maximum yield strength of 62.84 MPa and a ∼40% enhancement in impact energy absorption (25.4 J) compared to pure epoxy. Electromagnetic characterization reveals that while the composites provide moderate shielding in the GHz band (SET up to ∼4 dB at 4 wt.%), they exhibit exceptional, absorption-dominated shielding in the THz band, with the 4 wt.% composite attenuating over 99% of incident waves. Crucially, all composites retained high electrical insulation, comparable to neat epoxy. The synergistic enhancement is attributed to MXene’s role in stress transfer, crack pinning, the formation of local conductive networks, and interfacial polarization effects. • MXene (2 wt.%) optimizes epoxy’s yield strength (62.84 MPa) and impact resistance (25.4 J). • 4wt.% MXene achieves >4 dB GHz shielding and >99% THz attenuation via dual mechanisms. • Interfacial polarization and conductive networks enable EMI shielding without sacrificing insulation. • MXene mitigates stress concentration, enhancing energy dissipation and crack resistance. • Balanced multifunctionality suits extreme environments in military and aerospace systems.