Analysis of atomic oxygen erosion resistance mechanism of polyimide composite materials enhanced by polyhydroxysilylazane.

[Display omitted] • PHSN Enhancement: Novel cage-like PHSN boosts polyimide materials' AO resistance. Key for aerospace. • Molecular Dynamics: Reveals PI/PHSN's AO resistance via reaction pathways and surface analysis. • DFT Analysis: Uses density functional theory to identify AO reaction sites on PHSN, inhibiting volatilization. • Mechanism Discovery: Cage-like PHSN transforms AO to SiO 2 , offering molecular-level protection. • Aerospace Applications: Provides insights for AO erosion protection in spacecraft materials and design. Polyimide (PI) has excellent insulating properties and is widely used in aerospace electrical transmission devices and equipment. Polysilazane coatings have demonstrated excellent resistance to reactive atomic oxygen (AO). However, the understanding of the atomic oxygen erosion mechanism for polymer materials mixed with polysilazane components remains limited. In this study, a cage-like polyhydroxysilylazane (PHSN) primarily composed of silicon and nitrogen was designed. Two PI/PHSN hybrid structures were established, and their resistance to AO erosion, reaction pathways, and surface separation products were explored through reactive molecular dynamics simulations. Density functional theory (DFT) was employed to analyze the molecular orbitals of PHSN at different stages, predicting possible reaction sites for AO. The natural binding of generated small molecular fragments to PHSN side chains was studied through binding energy, revealing the volatilization inhibition mechanism of these small molecular fragments. Results indicate that the added cage-like polyhydroxysilylazane enhances the polymer's resistance to AO erosion by absorbing AO and converting it into SiO 2. This study explores the protective behavior of PHSN nano-cages at the molecular level, providing a new perspective for the design of AO erosion protection systems. [ABSTRACT FROM AUTHOR]