Oxidation-resistant, stable and flexible Ti₃C₂T_x MXene/Polyimide composites for high-performance electromagnetic interference shielding and thermal management

Ti₃C₂T_x MXene with outstanding physicochemical properties have shown huge potential in electromagnetic interference (EMI) shielding applications. However, the poor chemical stability and mechanical fragility have seriously hindered their practical use. Herein, we developed a novel pyrimidine-containing polyimide (PPI) and constructed Ti₃C₂T_x/PPI (MP) composite films. The incorporation of PPI not only suppresses the oxidation of Ti₃C₂T_x by forming Ti-N_x interactions between the nitrogen-rich pyrimidine rings of PPI and the Ti centers of Ti₃C₂T_x, but also enhances mechanical strength and durability of the composite film across a wide temperature range (-196–250 ℃). Compared with Ti₃C₂T_x film, the MP film exhibits significantly improved oxidation resistance, which the EMI SE of MP film did not decrease after 14 days in 80 ℃/80 RH environment when the weight ratio of Ti₃C₂T_x and PPI reaches 11:4. Merely 1.4 dB decrease in EMI SE of the MP film was revealed after 200,000 bending cycles with a radius of 2 mm, and the EMI SE remained virtually unchanged after bending in liquid N₂. Moreover, the composite film demonstrates excellent thermal management properties, including rapid thermal response, efficient electrothermal conversion, excellent durability and stability. The combination of desirable EMI shielding ability, ultrahigh flexibility, superior stability and durability, as well as ideal thermal management performance gives this material excellent potential for various applications.