High wear/corrosion resistance of PI coating: Exploration via interfaces, bonding, and structure

This study discusses the mechanism by which Ti₃C₂T_x MXene enhances the wear/corrosion resistance of polyimide (PI) coatings from the perspectives of interface interaction, bonding and filler structure. Despite the excellent performance of Ti₃C₂T_x MXene, its challenges in forming strong interface and strong bonding in PI limit its protection efficiency. To address this, we innovatively prepared amino-functionalized Ti₃C₂T_x nanoflowers (Ti₃C₂T_x@PEI) and uniformly dispersed them in the PI matrix as an enhancer. The results show that Ti₃C₂T_x@PEI achieves optimal protection of PI (the PI composite coating containing Ti₃C₂T_x@PEI nanoflowers (PMX–PI)). Under high loading, the wear rate of the PMX–PI composite coating is only 6.23×10⁻⁵ mm³·N⁻¹·m⁻¹. After the 4-week immersion test, the highest low-frequency impedance modulus (|Z|_0.01Hz) value of 3.73×10⁷ Ω·cm², approximately two orders of magnitude higher than that of the PI, is maintained. The coating resistance (R_c) is 1.81×10⁶ Ω·cm², which is approximately 2.2 times greater than that of PI (8.07×10⁵ Ω·cm²). According to Materials Studio (MS) calculations, Ti₃C₂T_x@PEI has the highest affinity for the PI precursor (polyamic acid, PAA), with an interaction energy of −21.41 kcal·mol⁻¹. Additionally, the –NH₂ groups in Ti₃C₂T_x@PEI are effectively utilized to form –CON– groups through dehydration condensation with –COOH groups in PAA at high temperature. These strong interactions and bonds promote uniform dispersion, filling the structural defects of PI.