Exploration on the tribological mechanisms of polyimide with different molecular structures in different temperatures

[Display omitted] •The incorporation of sulfur and fluorine atoms decreases polyimide mechanical properties.•The wear resistance of FPI and SPI is lower than PI.•The interaction potential energies of SPI and FPI are larger than that of PI due to the polarization of F and S.•The friction and wear almost becomes terrible with the temperature increasing. In order to explore the friction and wear mechanisms of polyimide with metal, this work addressed the tribological properties of the polyimide with different molecular structures in a wide temperature range. It was found that the incorporation of fluorine and sulfur atoms into polyimide had a significant effect on their mechanical and tribological properties. Generally, the wear rates of FPI and SPI are much higher than PI, and FPI displays the worst friction coefficient. To deeper reveal the fundamental reasons, the FTIR, XPS, EDS, SEM characterizations were carried out combined with molecular dynamic simulation. The calculation results from the Molecular Dynamics model between PI and Fe showed that the interaction potential energy of SPI and FPI was larger than that of PI due to the polarization of F and S. Judged from the structures of transfer film, SPI and FPI was easily adhered on the surface of counterpart, even chemical reaction. The XPS analysis further confirmed the possibility of tribo-chemical reactions between SPI/FPI and Fe. This study will provide the theoretical guidance for other polymer molecular design and its tribological research.