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 micro systems. To date, SSL systems have been realized for graphite flakes interacting with both two-dimensional materials and three-dimensional materials such as metal and ceramics. However, current research on SSL lacks exploration on 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. Results show that an 8μm graphite flake exhibits an ultralow friction coefficient of 1.6×10^-4 on the smooth PI surface under the normal forces ranging from 89 μN to 178 μN. Atomic Force Microscopy (AFM) and Raman spectroscopy confirm a wear-free state in friction zone. Furthermore, Focused Ion Beam / Scan 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 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.