三硅醇苯基POSS复合聚酰亚胺薄膜的制备与抗原子氧侵蚀性能研究

低地球轨道上运行的航天器表面材料尤其是聚合物材料极易受到原子氧侵蚀。以三硅醇苯基笼型聚倍半硅氧烷（TSP-POSS）为填料，以PMDA-ODA型聚酰亚胺（PI）为基体，通过机械共混法制备一系列复合薄膜，系统研究TSP-POSS的引入对复合薄膜耐热性能、光学性能以及抗原子氧侵蚀性能的影响。结果表明:TSP-POSS与PMDA-ODA型聚酰胺酸（PAA）具有良好的相容性，复合溶液均匀，储存稳定性优良；PAA/TSP-POSS复合溶液热酰亚胺化后形成的PI/TSP-POSS复合薄膜在TSP-POSS含量（质量分数）低于25%时可保持良好的均匀性；TSP-POSS的加入可在一定程度上提高复合薄膜的光学透明性，且对复合薄膜耐热性能的影响较小；引入TSP-POSS可以显著提高PMDA-ODA薄膜的抗原子氧性能，经受累积注量达4.02×1020 atoms/cm2的原子氧侵蚀后，TSP-POSS含量为25%的复合薄膜的原子氧剥蚀率为2.2×10-25 cm3/atom，仅为不含TSP-POSS薄膜的7.33%。

Preparation and atomic oxygen erosion properties of trisilanolphenyl-POSS combined polyimide films

The surface materials, especially, the polymer materials, used in spacecraft operating in low Earth orbit, may be greatly damaged when eroded by the atomic oxygen (AO). A series of the polyimide (PI) composite films are prepared via the physical blending of the PMDA-ODA matrix and the trisilanolphenyl polyhedral oligomeric silsesquioxane (TSP-POSS) additives. The effects of the incorporation of the TSP-POSS additives on the properties of the composite films, including the thermal stability, the optical properties, and the atomic oxygen resistance are systemically studied. The experimental results indicate that the TSP-POSS additives exhibit a good miscibility with the PMDA-ODA poly (amic acid) (PAA), and the homogeneous PAA/TSP-POSS composite solutions with a good storage stability are obtained. The PI/TSP-POSS composite films with loading amounts varied from 0 to 25% are successfully prepared by the high temperature imidization of the PAA/TSP-POSS solution. The composite films exhibit a good uniformity with the loading amount of the TSP-POSS up to 25%. The incorporation of the TSP-POSS additive improves the optical transparency of the derived composite films, with no impairment of the thermal properties of the pristine PI-0 film. Last but not the least, the incorporation of the TSP-POSS can significantly enhance the atomic oxygen resistance of the PI-0 films. During the AO exposure in the ground-based simulation test with the fluence of 4.02×1020 atoms/cm2, the PI-25 exhibits an erosion yield of 2.2×10-25 cm3/atom, which is only 7.33% of that of the pristine PI-0 film.