Recently, the research team led by Associate Professor Zhang Sizhao at the International Innovation Institute of JXUST has achieved significant progress in the development of aerogel thermal protection materials for aerospace applications under extreme conditions. The study unveils the in-situ encapsulation growth mechanism of polyimide aerogel (PIA) network skeletons. By employing focused ion beam (FIB) cutting to analyze micro-nano network structures, the team elucidated the formation mechanism of aerogel skeletons and successfully engineered PIA with exceptional high-temperature resistance and deep-cryogenic tolerance under extreme thermal gradients (ΔT = 496°C).
The groundbreaking findings, titled "High-Temperature Resistant Polyimide Aerogels with Extreme Condition Tolerance Constructed by in Situ Skeleton Encapsulation Growth," were published in Advanced Functional Materials (Impact Factor: 18.5), a top-tier international journal in materials science.
Polyimide aerogels, renowned for their superior thermal insulation, thermostability, and mechanical strength, are prime candidates for advanced aerospace thermal protection systems. However, conventional PIAs suffer from poor dimensional stability under high-temperature conditions, leading to significant degradation of key properties such as heat resistance and insulation performance, thereby limiting their applicability in extreme environments. To address these challenges, the team proposed an in-situ skeleton encapsulation growth strategy. By integrating high-performance polyimide aerogel synthesis with micro-nano-scale encapsulation of the aerogel skeleton using polymethylsiloxane (derived from hydrolyzed organosilane precursors), the researchers achieved multifunctional integration of high-temperature resistance, cryogenic tolerance, efficient thermal insulation, and flame retardancy in PIA.
Key experimental results demonstrate that the optimized PIA exhibits a 201.7°C temperature differential between hot and cold surfaces under a 300°C heat source, highlighting its exceptional insulation performance. Remarkably, the aerogel maintains outstanding dimensional stability at 300°C, with a linear shrinkage rate of only 1.11%—a 98.04% reduction compared to intrinsic PIAs. Notably, the operational temperature limit of this aerogel is elevated by 100°C relative to previously reported PIAs (which typically exhibit thermal shrinkage at 200°C). This enhancement stems from the polymethylsiloxane encapsulation layer, which shields the matrix skeleton from high-temperature erosion, prevents nanopore collapse, and effectively suppresses thermal shrinkage.
The study further subjected the aerogel to rigorous thermal shock tests. Under high-low temperature alternating cycles (ΔT = 270°C), the PIA demonstrated a minimal linear shrinkage of 0.70% even after 1,000 cycles. In extreme thermal cycling conditions (ΔT = 496°C), the material retained structural integrity with a shrinkage rate of 1.09% after 10 cycles. These results underscore the aerogel’s potential to meet stringent demands for aerospace thermal protection materials in harsh operational environments.
Paper Link:
https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202500881
