Wang Zhenzhong, Wang Xiaolei, Yuan Shunqi, Ren Xi, Yang Changxu, Han Shujun, Qi Yuexin, Li Duanyi, Liu Jingang
Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.
RAYITEK Hi-Tech Film Company, Co. Ltd., Shenzhen 518105, China.
Polymers (Basel). 2024 Oct 9;16(19):2845. doi: 10.3390/polym16192845.
Optically transparent polyimide (PI) films with good atomic oxygen (AO) resistance have been paid extensive attention as thermal controls, optical substrates for solar cells or other components for low Earth orbit (LEO) space applications. However, for common PI films, it is usually quite difficult to achieve both high optical transparency and AO resistance and maintain the intrinsic thermal stability of the PI films at the same time. In the current work, we aimed to achieve the target by using the copolymerization methodology using the fluorinated dianhydride 9,9-bis(trifluoromethyl)xanthene-2,3,6,7-tetracarboxylic dianhydride (6FCDA), the fluorinated diamine 2,2-bis [4-(4-aminophenoxy)phenyl]hexafluoropropane (BDAF) and the polyhedral oligomeric silsesquioxane (POSS)-containing diamine -[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS) as the starting materials. The fluoro-containing monomers were used to endow the PI films with good optical and thermal properties, while the silicon-containing monomer was used to improve the AO resistance of the afforded PI films. Thus, the 6FCDA-based PI copolymers, including 6FCPI-1, 6FCPI-2 and 6FCPI-3, were prepared using a two-step chemical imidization procedure, respectively. For comparison, the analogous PIs, including 6FPI-1, 6FPI-2 and 6FPI-3, were correspondingly developed according to the same procedure except that 6FCDA was replaced by 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). Two referenced PI homopolymers were prepared from BDAF and 6FDA (PI-ref1) and 6FCDA (PI-ref2), respectively. The experimental results indicated that a good balance among thermal stability, optical transparency, and AO resistance was achieved by the 6FCDA-PI films. For example, the 6FCDA-PI films exhibited good thermal stability with glass transition temperatures (T) up to 297.3 °C, good optical transparency with an optical transmittance at a wavelength of 450 nm (T) higher than 62% and good AO resistance with the erosion yield () as low as 1.7 × 10 cm/atom at an AO irradiation fluence of 5.0 × 10 atoms/cm. The developed 6FCDA-PI films might find various applications in aerospace as solar sails, thermal control blankets, optical components and other functional materials.
具有良好抗原子氧（AO）性能的光学透明聚酰亚胺（PI）薄膜作为热控材料、太阳能电池的光学基板或低地球轨道（LEO）空间应用的其他组件，受到了广泛关注。然而，对于普通PI薄膜来说，通常很难同时实现高光学透明度和抗AO性能，并保持PI薄膜的固有热稳定性。在当前工作中，我们旨在通过使用共聚方法来实现这一目标，该方法使用含氟二酐9,9-双（三氟甲基）氧杂蒽-2,3,6,7-四羧酸二酐（6FCDA）、含氟二胺2,2-双[4-（4-氨基苯氧基）苯基]六氟丙烷（BDAF）和含多面体低聚倍半硅氧烷（POSS）的二胺-[(七异丁基-POSS)丙基]-3,5-二氨基苯甲酰胺（DABA-POSS）作为起始原料。含氟单体用于赋予PI薄膜良好的光学和热性能，而含硅单体用于提高所得PI薄膜的抗AO性能。因此，分别采用两步化学亚胺化程序制备了基于6FCDA的PI共聚物，包括6FCPI-1、6FCPI-2和6FCPI-3。为了进行比较，按照相同程序相应地制备了类似的PI，包括6FPI-1、6FPI-2和6FPI-3，只是用4,4'-（六氟异丙基）二邻苯二甲酸酐（6FDA）代替了6FCDA。分别由BDAF和6FDA（PI-ref1）以及6FCDA（PI-ref2）制备了两种参考PI均聚物。实验结果表明，6FCDA-PI薄膜在热稳定性、光学透明度和抗AO性能之间实现了良好的平衡。例如，6FCDA-PI薄膜表现出良好的热稳定性，玻璃化转变温度（T）高达297.3℃，良好的光学透明度，在450nm波长处的透光率（T）高于62%，以及良好的抗AO性能，在AO辐照通量为5.0×10 atoms/cm时，侵蚀产率（）低至1.7×10 cm/atom。所开发的6FCDA-PI薄膜可能在航空航天领域作为太阳帆、热控毯、光学组件和其他功能材料找到各种应用。
