Safe Synthesis and Interfacial Optimization of Polyimide Composite Aerogels with Enhanced Mechanical and High-Temperature Resistance Performance

In the industrialization of polyimide (PI) aerogel synthesis, developing safe and practical pathways and optimizing interface performance remain two pivotal challenges. This study introduces a nonrestrictive dehydrating agent and catalyst system to address safety issues associated with traditional hazardous chemicals like acetic anhydride and pyridine, thereby facilitating the large-scale production of PI aerogels. Polycrystalline mullite fiber (PMF) was selected to couple with PI aerogel to enhance the mechanical strength and high-temperature resistance performance. Notably, to improve the interfacial compatibility of composite materials, silane coupling agent KH550 (APTES) functions as a “molecular bridge”, playing an essential role in the interfacial cross-linking between PI aerogel and PMF. Overall, the innovative method not only reduces the shrinkage rate of PI aerogels, but also lowers the thermal conductivity of PI composite aerogels from 0.0473 W·m–1·K–1 to 0.0367 W·m–1·K–1. Furthermore, the high-temperature resistance properties of PI composite aerogels were improved to 500 °C with no obvious structural collapse. The optimal 2% PMF-APTES/PI aerogel demonstrates significant potential to replace conventional materials in a wide range of applications.