Mechanisms of atomic oxygen resistance in POSS-enhanced fluorinated polyimide and high-frequency insulation stability based on PLS analysis

Fluorinated polyimide (FPI) is widely used in high-frequency electronics and aerospace insulation applications owing to its low dielectric loss and excellent stability; however, the degradation behavior and regulatory mechanisms of its high-frequency insulation performance after atomic oxygen (AO) erosion remain unclear. In this study, FPI/POSS composite films with different contents of polyhedral oligomeric silsesquioxane (POSS) were prepared. An AO ground-simulated erosion system was employed to evaluate the protective effectiveness of POSS on FPI and its underlying mechanisms. Combined with vacuum high-frequency partial discharge testing and a partial least squares (PLS) regression model, the effects of AO erosion and material structural regulation on the evolution of insulation lifetime were systematically investigated. The results show that pure FPI exhibits pronounced surface roughening and oxidative erosion after AO bombardment, whereas the introduction of POSS induces the in-situ formation of a dense SiO 2 passivation layer, effectively suppressing further polymer etching. Meanwhile, the FPI/POSS system demonstrates a higher discharge inception voltage, lower dielectric loss, and a longer insulation lifetime. This work provides a new perspective for evaluating insulation reliability and optimizing the structural design of polyimide materials for space service environments.