In the contemporary pursuit of ensuring long-term lubrication for transmission units operating under harsh conditions, significant challenges remain. Researchers have been investigating porous polymer materials as a potential solution; however, achieving exceptionally low friction and wear has proven elusive. To address this issue, we have developed a novel porous fluorinated polyimide (PPIF-250) characterized by superior mechanical performance, heat resistance, and higher oil content and retention compared to other PPIs with comparable pore size and porosity. Extensive lubrication testing under varying conditions has demonstrated that PPIF-250 achieves remarkably low friction and wear characteristics, even under high FV values, representing a significant advancement in this field. Furthermore, our findings indicate that the polarity of base oils plays a crucial role in determining the oil content and retention of PPIF-250. Specifically, the integration of PPIF-250 with a tailored PEG-200 structure results in significantly improved oil content, retention, and long-term lubrication relative to other base oils. This improvement is attributed to the formation of high-load capacity boundary films within the PPIF-250 matrix, comprising oxidation processes involving carboxyl functional groups that chelate with iron or its oxides, alongside multi-layer adsorption films stabilized by intermolecular hydrogen bonding and Van der Waals forces. These insights will be instrumental in the development of more efficient and effective lubrication materials to meet the demands of modern technology.

Polyimide composites have been extensively used as motion components under extreme conditions for their thermal stability and special self-lubricating performance. In the present study, Ag-Mo hybrids as lubricant fillers were incorporated into thermosetting polyimide to prepare a new type of tribo-materials (TPI-1) at high temperature. Comprehensive investigations at different temperatures reveal that the newly developed TPI-1 exhibits a better reduction in friction and wear rate below 100 ^°C, but all of them increase significantly when the bulk temperature exceeds 250 ^°C. The wear mechanisms demonstrated that sandwich-like tribofilms with different layers were established at different temperatures, which was further verified by characterization of scanning electron microscope (SEM), Raman spectroscopy, and transmission electron microscope (TEM). Considering the high-performance TPI coupled with Ag-Mo hybrids, we anticipate that further exploration would provide guidance for designing TPI tribo-materials that would be used at high temperatures.