Research of Ferric Ion Regulation on a Polyimide/C-MXene Microcellular Composite Film

This paper established a new kind of polyimide/C-MXene composite films with a microcellular structure for electromagnetic interference shielding through solution mixing and liquid phase separation methods. Polyimide was used as the resin material, Ti₃C₂T MXene was used as the electromagnetic wave-shielding medium, l-citrulline was used as the surface modification agent, ferric trichloride (especially the ferric ion) was used as the cross-linking agent between the polyimide and modified C-MXene, and a microcell was used as the shielding structure. By adjusting the content of ferric ions, the foam structure, mechanical properties, thermal conductivity, and electromagnetic interference shielding efficiency of the polyimide/C-MXene microcellular composite film could be controlled. The higher the ferric ion content, the smaller the foam size and the higher the electromagnetic interference shielding efficiency. With increasing ferric ion content, the tensile strength and Young's modulus appeared to first increase and then decrease; when the ferric ion content was 0.8 wt %, the tensile strength and Young's modulus reached their maximum values, which were 10.06 and 325.29 MPa, respectively. In addition, with increasing ferric ion content, the thermal insulation showed first decreasing and then increasing tendency; the lowest thermal conductivity was 0.17 W/(m·K) when the ferric ion content was 0.8 wt %.