Abstract: High-performance multifunctional polymeric materials integrated with high fire safety, excel-lent mechanical performances and electromagnetic interference (EMI) shielding properties have great prospects in practical applications. However, designing highly fire-safe and mechanically ro-bust EMI shielding nanocomposites remains a great challenge. Herein, hierarchical thermoplastic polyurethane/cyclophosphazene functionalized titanium carbide/carbon fiber fabric (TPU/CP-Ti₃C₂T_x/CF) nanocomposites with high fire safety and mechanical strength and toughness were prepared through the methods of melt blending, layer-by-layer stacking and thermocompression. The TPU/CP-Ti₃C₂T_x showed improved thermal stability. Moreover, the peak of heat release rate and total heat release of the hi-erarchical TPU sample containing 4.0 wt.% CP-Ti₃C₂T_x were respectively reduced by 64.4% and 31.8% relative to those of pure TPU, which were far higher than those of other TPU-based nanocomposites. The averaged EMI shielding effectiveness value of the hierarchical TPU/CP-Ti₃C₂T_x-2.0/CF nanocomposite reached 30.0 dB, which could satisfy the requirement for commercial applications. Furthermore, the ten-sile strength of TPU/CP-Ti₃C₂T_x-2.0/CF achieved 43.2 MPa, and the ductility and toughness increased by 28.4% and 84.3% respectively compared to those of TPU/CF. Interfacial hydrogen bonding in combination with catalytic carbonization of CP-Ti₃C₂T_x nanosheets and continuous conductive network of CF were re-sponsible for the superior fire safety, excellent EMI shielding and outstanding mechanical performances. This work offers a promising strategy to prepare multifunctional TPU-based nanocomposites, which have the potential for large-scale application in the fields of electronics, electrical equipment and 5G facilities.

Key words: Hierarchical structure, Fire safety, Electromagnetic interference shielding, Mechanical strength and toughness, Air assisted thermocompression