Mechanically strong and folding-endurance Ti₃C₂T_x MXene/PBO nanofiber films for efficient electromagnetic interference shielding and thermal management

Electromagnetic interference (EMI) shielding materials with excellent flexibility and mechanical properties and outstanding thermal conductivity have become a hot topic of research in functional composites. In this study, the “sol–gel-film conversion technique” is used to assemble polyetherimide-functionalized Ti₃C₂T_x nanosheets (f-Ti₃C₂T_x) with poly(p-phenylene-2,6-benzobisoxazole) (PBO) nanofibers (PNFs), followed by dialysis and vacuum drying to prepare f-Ti₃C₂T_x/PNF films with lamellar structures. When the loading of f-Ti₃C₂T_x is 70 wt%, the f-Ti₃C₂T_x/PNF film presents optimal comprehensive properties, with an EMI shielding effectiveness (SE) of 35 dB and a specific SE/thickness ((SSE, SE/density)/t) of 8211 dB cm²/g, a tensile strength of 125.1 MPa, an in-plane thermal conductivity coefficient (λ) of 5.82 W/(m K), and electrical conductivity of 1943 S/m. After repeated folding for 10,000 cycles, the EMI SE and the tensile strength of f-Ti₃C₂T_x/PNFs films still remain 33.4 dB and 116.1 MPa, respectively. Additionally, the f-Ti₃C₂T_x/PNF film also shows excellent thermal stability, flame retardancy, and structural stability. This would provide a novel method for the design and fabrication of multifunctional composite films and considerably expand the applications of MXene- and PNF-based composites in the fields of EMI shielding and thermal management.