Zhang Yan, Wu Hao, Guo Yi-Dan, Yang Yan-Bin, Yu Qiang, Liu Jin-Gang, Wu Bo-Han, Lv Feng-Zhu
Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.
Space Materials and Structure Protection Division, Beijing Institute of Spacecraft Environment Engineering, Beijing 100094, China.
Nanomaterials (Basel). 2021 Jan 8;11(1):141. doi: 10.3390/nano11010141.
For the development of spacecraft with long-servicing life in low earth orbit (LEO), high-temperature resistant polymer films with long-term atomic oxygen (AO) resistant features are highly desired. The relatively poor AO resistance of standard polyimide (PI) films greatly limited their applications in LEO spacecraft. In this work, we successfully prepared a series of novel AO resistant PI composite films containing nanocaged polyhedral oligomeric silsesquioxane (POSS) components in both the PI matrix and the fillers. The POSS-containing PI matrix film was prepared from a POSS-substituted aromatic diamine, -[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS) and a common aromatic diamine, 4,4'-oxydianline (ODA) and the aromatic dianhydride, pyromellitic dianhydride (PMDA) by a two-step thermal imidization procedure. The POSS-containing filler, trisilanolphenyl POSS (TSP-POSS) was added with the fixed proportion of 20 wt% in the final films. Incorporation of TSP-POSS additive apparently improved the thermal stability, but decreased the high-temperature dimensional stable nature of the PI composite films. The 5% weight loss temperature () of POSS-PI-20 with 20 wt% of DABA-POSS is 564 °C, and its coefficient of linear thermal expansion (CTE) is 81.0 × 10/K. The former is 16 °C lower and the latter was 20.0 × 10/K higher than those of the POSS-PI-10 film ( = 580 °C, CTE = 61.0 × 10/K), respectively. POSS components endowed the PI composite films excellent AO resistance and self-healing characteristics in AO environments. POSS-PI-30 exhibits the lowest AO erosion yield () of 1.64 × 10 cm/atom under AO exposure with a flux of 2.51 × 10 atoms/cm, which is more than two orders of magnitude lower than the referenced PI (PMDA-ODA) film. Inert silica or silicate passivation layers were detected on the surface of the PI composite films exposed to AO.
对于在低地球轨道（LEO）具有长使用寿命的航天器的发展而言，具有长期抗原子氧（AO）特性的耐高温聚合物薄膜是非常需要的。标准聚酰亚胺（PI）薄膜相对较差的抗AO性能极大地限制了它们在LEO航天器中的应用。在这项工作中，我们成功制备了一系列新型的抗AO的PI复合薄膜，其在PI基体和填料中均含有纳米笼状的多面体低聚倍半硅氧烷（POSS）成分。含POSS的PI基体薄膜由一种POSS取代的芳香二胺-[(七异丁基-POSS)丙基]-3,5-二氨基苯甲酰胺（DABA-POSS）、一种常见的芳香二胺4,4'-氧二苯胺（ODA）和芳香二酐均苯四甲酸二酐（PMDA）通过两步热亚胺化程序制备而成。含POSS的填料三硅醇苯基POSS（TSP-POSS）以20 wt%的固定比例添加到最终薄膜中。TSP-POSS添加剂的加入明显提高了热稳定性，但降低了PI复合薄膜的高温尺寸稳定性。含20 wt% DABA-POSS的POSS-PI-20的5%失重温度（）为564℃，其线性热膨胀系数（CTE）为81.0×10⁻⁶/K。前者比POSS-PI-10薄膜（=580℃，CTE=61.0×10⁻⁶/K）低16℃，后者比其高20.0×10⁻⁶/K。POSS成分赋予了PI复合薄膜在AO环境中优异的抗AO性能和自修复特性。在通量为2.51×10¹⁵原子/cm²的AO暴露下，POSS-PI-30表现出最低的AO侵蚀产率（）为1.64×10⁻²⁵cm³/原子，比参考的PI（PMDA-ODA）薄膜低两个多数量级。在暴露于AO的PI复合薄膜表面检测到了惰性二氧化硅或硅酸盐钝化层。
