Mechanisms of enhanced durability in fluorinated polyimide based on POSS during electro-thermal aging

Fluorinated polyimide (FPI) is widely used in high-frequency electronic devices and aerospace applications due to its outstanding insulation properties and chemical stability. However, its degradation mechanisms under electro-thermal aging remain poorly understood. Polyhedral oligomeric silsesquioxane (POSS), as a nanofiller, offers excellent thermal stability and flame retardancy, yet studies on the electro-thermal aging resistance and chemical transformation mechanisms of FPI/POSS nanocomposites are still limited. This study employs reactive molecular dynamics (ReaxFF-MD) simulations, combined with vibrational energy distribution analysis, to investigate the electro-thermal aging mechanisms of FPI/POSS nanocomposites. Additionally, density functional theory (DFT) is used to examine the electron transfer pathways of FPI molecules and the reactive site changes in POSS cages under electric fields. The results demonstrate that POSS achieves higher vibrational energy and structural stability under electro-thermal conditions, significantly raising the thermal decomposition threshold of FPI molecular chains. This reduces the release of volatile products and substantially enhances the electro-thermal aging resistance of the composites.