Lubrication mechanism of polyimide/V₂CT_x MXene composites based on surface chemistry

A series of polyimide (PI)/V₂CT_x MXene composites was synthesized via polyamide acids (PAA) and two-dimensional (2D) V₂CT_x MXene obtained by etching precursor V₂AlC. PI/V₂CT_x MXene composites with different mass ratios were obtained by blending and heating with PAA. The results showed that V₂CT_x MXene has excellent dispersion in PI. In particular, V₂CT_x MXene exhibited excellent friction reduction and anti-wear properties as a solid lubricant additive, and the wear rate (WR) was reduced by 43.2% by incorporating only 0.8 wt% of V₂CT_x MXene in the pristine PI and 71.9% by incorporating 1.2 wt%. Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) analyses showed that the continuous transfer film consisting of a high proportion of tribo-chemical products formed on the contact surface is significant to improve the lubrication performances of the PI composites. This work broadens the application of MXene in the field of tribology and contributes to energy conservation and sustainable development of human society. Highlights: The tribological properties could be tuned by changing the ratio of PI to V₂CT_x MXene. The WR of PI composites was reduced by 71.9% with incorporating 1.2 wt% of V₂CT_x MXene. The formation of transfer films on the contact surface is significant for improving anti-wear of PI.