表面化学改性的耐原子氧聚酰亚胺材料的制备及侵蚀机理研究

Carboxyl groups are generated on the Upilex-S polyimide film surface via surface-hydrolization method, which are then reacted with POSS structures aiming at enhancing the atomic oxygen erosion resistance of polyimide film. By adjusting the surface quantity of carboxyl groups and the length of linking groups between POSS and the polyimide surface, the packing density of POSS on polyimide surface can be increased without loss of bulk properties of polyimide film. The relationship between surface modification level and the atomic oxygen erosion resistance can also be examined. Moreover, the polyimide surfaces linked with POSS structures with short linking groups, followed by linking those with longer longer linking groups, make it realized that the multilayered POSS packing on the surfaces of polyimde on the molecular level. It is expected that the packing patten can greatly improve the density of POSS on polyimide film and thus lead to higher atomic oxygen erosion resistance. The polyimide materials that serve better on flight vehicles in LEO can be obtained by contrasting the mophology, X-ray Photoelectonic Spectra and mass loss of polyimide films before and after the ground simulation atomic oxygen experiments.The project will contribute to the optimization of polyimide materials with high atomic oxygen reisistance and provide both experimental and theoretical support to the atomic oxygen erosion mechanism study.

本项目旨在利用表面官能团化的方法来修饰Upilex-S型聚酰亚胺，在其表面产生羧基，之后通过羧基引入POSS基团，以此来增强聚酰亚胺的耐原子氧能力。在不改变聚酰亚胺本体性质的前提下，通过控制表面官能团的密度、POSS与聚酰亚胺表面的连接基团长度等要素来考察POSS在聚酰亚胺表面的致密度，并以此研究聚酰亚胺表面官能团化程度与耐原子氧能力之间的关系。另外，借助具有不同长短连接基团的POSS结构与聚酰亚胺表面依次进行接枝反应，实现分子层次上POSS基团在聚酰亚胺表面的多层堆积。希望这种堆积可以进一步增加POSS的致密程度，赋予聚酰亚胺材料更高的耐原子氧能力。通过比较原子氧试验前后材料的形貌、X光电子能谱以及质量损失等性质来研究表面改性聚酰亚胺的侵蚀原理，并筛选出更适合应用于低地球轨道上飞行器的聚酰亚胺材料。本项目将为制备具有高耐原子氧能力的聚酰亚胺材料提供重要思路。

本项目旨在利用表面改性的方法来修饰聚酰亚胺（PI）薄膜材料，通过溶液处理等方法，在其表面活化产生羧基等活性基团。之后利用表面接枝方法引入富含Si元素的笼状寡聚倍半硅氧烷（POSS）分子。通过选用不同接枝POSS分子种类和PI膜活化的策略来调控POSS基团在PI膜上的接枝密度。XPS结果表明，改性后的PI膜的Si含量最多可达9.64%。通过原子氧辐照试验考察了改性后的PI膜的耐原子氧性能，其中POSS-epoxy改性后的PI膜耐原子氧性能最好，其原子氧剥蚀产率达到了0.44 cm3/O atom。扫描电镜结果也表明，较其它经辐照后的PI膜，其形貌变化不明显；XPS上也出现了结合能在104 eV的Si信号，说明经过原子氧辐照后，POSS结构中的Si被氧化成为类SiO2结构，提高了PI膜的抗原子氧侵蚀能力。