Innovative Polyimide Modifications for Aerospace and Optoelectronic Applications: Synergistic Enhancements in Thermal, Mechanical, and Optical Properties

This study pioneers a molecular topology engineering strategy by incorporating a twisted diamine motif into polyimide (PI) backbones, achieving an unprecedented integration of thermal stability, mechanical robustness, and optoelectronic functionality that surpasses conventional high-performance PIs. Unlike traditional PIs constrained by performance trade-offs (e.g., compromised flexibility for thermal resistance or sacrificed bulk properties for functionalization), the modified PI demonstrates a breakthrough balance: thermal degradation temperature (T5%) exceeding 560 °C, glass transition temperature (Tg) of 380 °C, and tensile strength of 160–180 MPa. Crucially, it exhibits green fluorescence (505–515 nm) under 365/467 nm excitation─a previously unreported optical capability in PIs. Molecular dynamics/density functional theory (MD/DFT) simulations coupled with UV–vis and mechanical analyses reveal that the twisted conformation induces molecular orbital reorganization and optimized stress distribution, establishing a design framework for multifunctional PIs. In contrast to additive-dependent modification approaches, this topology-driven strategy enables intrinsic multifunctionality while maintaining compatibility with industrial polymerization processes, overcoming scalability challenges in functional PI production. The work redefines PI applications in aerospace composites, optoelectronic systems, and next-gen sensors under extreme conditions, while providing a paradigm for developing performance-integrated polymers through rational topological design.