Synergistic enhancement of EMI shielding and interfacial properties in CF/PEKK composites via electrostatic self-assembly of aminated MXene and SPEKK

Structural-functional integrated composites represent a key trend in aerospace and smart manufacturing applications. In this work, inorganic two-dimensional MXene (Ti₃C₂T_x) synergistic organic sulfonated polyetherketoneketone (SPEKK) was employed to increase the EMI shielding and interfacial properties of carbon fiber reinforced polyetherketoneketone (CF/PEKK) composites via electrostatic self-assembly. By means of static cling, the aminated MXene (MXene-NH₂) with positive charge and negatively charged SPEKK were sequentially assembled on the negatively charged CF surfaces to form an effective interfacial layer. Subsequently, CF/PEKK composites were prepared by molding process. The resultant CF/PEKK composites achieved superior EMI shielding effectiveness of 44.6 dB, which was 60.4 % higher than that of unmodified CF/PEKK composites. The improvement of the shielding effectiveness might be due to increased interfacial polarization losses, ohmic losses and dipole polarization losses of the CF/PEKK composites by MXene-NH₂ and SPEKK against electromagnetic waves. Simultaneously, the flexural strength, flexural modulus and interlaminar shear strength of CF/PEKK composites achieved 1233 MPa, 86.47 GPa and 92 MPa, which were 35.0 %, 16.1 % and 26.0 % above those of virgin CF/PEKK composites, respectively. Such promotion in mechanical properties could originate from the comprehensive effect of static cling, hydrogen bonding and mechanical interlocking between MXene-NH₂ and CF, SPEKK, as well as π-π interactions, diffusion and entanglement between SPEKK and polyetherketoneketone (PEKK). Briefly, this study puts forward an effective interfacial modification technique for developing carbon fiber-reinforced thermoplastic composites with integrated structural and functional properties.