UV-Induced Synthesis of Hybrid HMDSO/SiO<sub>2</sub> Thin Films with Compositional Gradients for High-Performance Atomic Oxygen Resistance
Yi Li, Zhonghua Li, Yanchun He, Hu Wang, Kaifeng Zhang, Lü Yuan, Shengzhu Cao, Dongfeng Ma, Lin Li, Miao Yang, Hengjiao Gao, Kai Wang, Min Xu, Detian Li
Abstract
A flexible, dense, defect-free, highly adhesive, and highly dissociation energy-rich protective coating is essential to enhance the atomic oxygen (AO) resistance of polymeric materials in a low Earth orbit (LEO). In this work, a dense, defect-free hybrid HMDSO/SiO 2 thin film coating with compositional gradients on the surface of polyimide was synthesized using vacuum-ultraviolet (VUV) irradiation. The effects of VUV irradiation on the morphology, optical transmittance, and chemical components of plasma-polymerized HMDSO (pp-HMDSO) thin-film coatings deposited on the polyimide surface were investigated in depth. There were no defects such as cracks and holes in the surface morphology of pp-HMDSO films after VUV irradiation, but the surface roughness increased slightly, and the corresponding optical transmittance decreased slightly. The chemical components of pp-HMDSO films were changed in the depth direction starting from the top of the surface, forming hybrid HMDSO/SiO 2 thin films with compositional gradients. The component gradient HMDSO/SiO 2 composite coating further enhanced the atomic oxygen resistance of the polyimide due to the surface layer of the UV-modified coating enriched with high dissociation energy SiO x material. Therefore, this work provides a facile UV-induced synthesis method to prepare dense, defect-free, and highly dissociation energy-rich protective gradient coatings, which are promising not only for excellent AO protection in LEO but also for potential application in water–oxygen barrier films.