Unlocking polymer-based self-superlubricity: First demonstration of ultralow friction and wear at graphite–polyimide interfaces

A self-superlubricity (SSL) state, characterized by wear-free and ultralow friction between two solid surfaces, offers a significant solution to the challenges of friction and wear in microsystems. To date, SSL systems have been realized for graphite flakes interacting with both two-dimensional materials and three-dimensional materials such as metals and ceramics. However, current research on SSL lacks exploration of polymer-based materials, limiting the application of SSL technology in microsystems involving polymer components. Here, we experimentally demonstrate SSL between a graphite flake and a polyimide (PI) film. The results show that an 8 μm graphite flake exhibits an ultralow friction coefficient of 1.6×10⁻⁴ on the smooth PI surface under normal forces ranging from 89 to 178 μN. Atomic force microscopy (AFM) and Raman spectroscopy confirm a wear-free state in the friction zone. Furthermore, focused ion beam/scanning electron microscopy (FIB/SEM) reveals an intimately contacted graphite–PI interface, indicating large-area contact rather than point contact between the two interfaces. This work presents the first experimental realization of robust SSL at the graphite–polymer interface, substantially broadening the material applicability and functional potential for SSL technology. It also opens new avenues for investigating the mechanisms of self-superlubricity.