Wrinkle‐Engineered Strong and Flexible Ti ₃ C ₂ T _x MXene / PBO Heterostructure Films for Efficient Thermal Management and Electromagnetic Shielding

ABSTRACT Flexible polymer composites with integrated thermal conductivity and electromagnetic interference (EMI) shielding are vital for next‐generation electronics. However, balancing mechanical, thermal, and electrical performance remains challenging. Herein, we report a high‐performance heterostructure film fabricated from poly(p‐phenylene‐2,6‐benzobisoxazole) (PBO) nanofibers and Ti ₃ C ₂ T _x MXene nanosheets. A PBO‐modified MXene (mPM) composite was first prepared via vacuum‐assisted filtration. This mPM layer was subsequently deposited onto a homologous PBO sol, followed by an in situ confined sol–gel‐film conversion process to construct a wrinkled mPM/PBO heterostructure film. The resulting architecture integrates an electrically conductive top layer with a thermally conductive base layer, enabling an exceptional combination of high tensile strength (312.7 MPa), high toughness (57.3 MJ m ⁻³ ), superior in‐plane thermal conductivity (18.2 W m ⁻¹ K ⁻¹ ), and remarkable EMI shielding effectiveness (12291.5 dB cm ² g ⁻¹ ). Additionally, the film demonstrates outstanding photo‐ and electro‐thermal responsiveness. Notably, the engineered wrinkled morphology enhances shielding performance by promoting scattering and absorption losses while preserving mechanical flexibility with a low Young's modulus. This work offers a practical route toward multifunctional materials for wearable and flexible electronics.