Substantially Improved Electromagnetic Interference Shielding Performance of Gradient-Conductive Ti3C2 Tx MXene/Polyimide Composite Films

Polymer-based conductive nanocomposites are promising candidates for electromagnetic interference (EMI) shielding, which is crucial for ensuring the stable operation of electronic devices and protecting human health from electromagnetic radiation exposure. In this study, Ti3C2 T, MXene was incorporated for its electrical conductivity, while polyimide (PI) served as a protective matrix to prevent MXene oxidation, thus improving the composite's durability. A gradient-conductive Ti3C2 T x MXene/PI composite film was developed by systematically varying the concentrations of MXene and PI. The resulting gradient film exhibited superior EMI shielding performance, with a total shielding effectiveness (SET) averaging ~50.01 dB in the X-band frequency range (8-12.4 GHz). The absorption component (EMI SEA) dominated, reaching around 45.02 dB, while the reflection component (EMI SER) contributed minimally (~4.99 dB). The gradient-conductive structure, consisting of a less conductive top layer and a highly conductive bottom layer, facilitated effective absorption and reflection of electromagnetic waves, extending the dissipation path and enabling multiple internal reflections, thus minimizing secondary emissions. The composite demonstrated only a slight reduction (~4.67%) in its total EMI SET value (dropping to 47.66 dB) after being subjected to heat treatment at 150°C for three days under ambient conditions, indicating good thermal stability. This work presents a straightforward and cost-effective method for fabricating high-performance and sustainable EMI shielding materials, making them suitable for applications in wearable electronics and aerospace technology.