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Important Progress In Bionic Nanocomposite Films For Space Protection

2021/12/3 13:18:00 0

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Polyimide film has become an excellent material for "protective clothing" of space probe due to its excellent mechanical properties, excellent thermal stability and outstanding chemical resistance. However, like other hydrocarbon polymers, polyimide materials are also vulnerable to the attack of atomic oxygen in space environment, resulting in a sharp decline in their physical and mechanical properties. At present, there is no good solution to this problem. In addition, extreme environments such as cosmic ray radiation and space debris impact also put forward severe tests on its stability.

Fig. 1. The preparation process, microstructure, mechanical properties and atomic oxygen resistance of polyimide nano mica biomimetic composite membrane are illustrated

Recently, academician Yu Shuhong of the Chinese University of science and technology has developed a new type of polyimide nano mica composite membrane material for space protection applications. The unique bionic design of the material has greatly improved its mechanical properties and space extreme environmental tolerance. Inspired by the "brick mud" layered structure of natural mother of pearl, the researchers skillfully designed and constructed a polyimide mica nanocomposite membrane with a double-layer nacre like structure, which made the top layer of the film have more dense mica nanosheets. With the help of the intrinsic properties of mica and the advantages of the most building unit, the mechanical properties of the material were effectively improved, and the top layer of the polyimide mica nano composite membrane was made to be resistant to atomic oxygen, oxygen and oxygen The resistance to ultraviolet radiation and space debris has also been significantly improved. The research results are as follows: double layer nacre inspired polyimide mica nanocomposite films with excellent mechanical stability for Leo enviro "Nmental conditions" was published in the international journal advanced materials. Pan Xiaofeng, a special associate researcher of our university, and Wu Bao, a doctoral student, are the co first authors of the paper, while Gao huailing and Professor Yu Shuhong are the corresponding authors.

The researchers used the mica nanosheets (NAT. Commun. 2018, 9, 2974) which had excellent mechanical properties and UV shielding function and could be prepared in large scale as the building units. The polyimide mica nanocomposite films were assembled with polyimide precursors to make up for the deficiency of Polyimide by using the superior intrinsic properties of mica. Different from the previous single-layer structure design of nacre like nanocomposite films, in this study, the researchers constructed a polyimide mica nanocomposite film with a bilayer nacre like structure by changing the composition ratio and combining spraying with thermal curing, so that the top layer of the polyimide mica nanocomposite film has a more compact mica nano sheet (Fig. 1a-f). This design strategy not only improves the mechanical properties of the material, but also makes its upper surface more resistant to atomic oxygen, ultraviolet radiation and space debris.

The results show that the tensile strength, Young's modulus and surface hardness of the new biomimetic composite membrane are 125 MPa, 2.2 GPA and 0.37 GPA, respectively, which are 45%, 100% and 68% higher than those of pure polyimide membrane (Fig. 1g). Due to the unique double-layer nacre like structure and the inherent properties of mica nanosheets, the obtained bilayer polyimide mica composite films show better atomic oxygen resistance (corrosion rate ≈ 0.17) × Compared with the pure polyimide film, the single layer of polyimide mica composite film with mother of Pearl structure and the polyimide matrix composite material reported in the past. In addition, the UV aging resistance (313 nm) and high temperature stability (380oc) of the pure PI film were also significantly improved.

This kind of polyimide mica nanocomposite film with bilayer nacre like structure is expected to replace the existing polyimide based composite membrane material as an effective new spacecraft outer protection material, so as to be used in low orbit environment. The unique design strategy of double-layer mother of Pearl structure proposed in this study also provides a new idea for the design and construction of other high-performance nanocomposites.

This research has been supported by the National Natural Science Foundation of China (NSFC), National Natural Science Foundation of China (NSFC), Chinese Academy of Sciences (CAS), Central University Basic Research Fund, Anhui provincial university collaborative innovation project and China University of science and technology synchrotron radiation joint fund.