Structurally Engineered Polyimide Nanofiber Aerogels Enabling Large-Strain Shape Memory Performance

Polyimide (PI) aerogels with shape memory functionality are highly desirable for thermal insulation in aerospace applications, yet conventional PI aerogels suffer from susceptibility to collapse under compression and insufficient shape recovery at high strain. Herein, we report a series of shape memory polyimide nanofiber aerogels (PINFAs) featuring a lamella-nanofiber cross-linked architecture, fabricated by electrospinning polyamic acid nanofibers (PAANFs) followed by unidirectional freeze-drying and thermal imidization. By systematically tuning the mass ratio of PAANFs to triethylamine (TEA), we precisely regulated the proportion of lamellas to nanofibers in the scaffold. The as-prepared PINFAs with the stable lamella and nanofiber cross-linking structure exhibited low shrinkage (28.2%), high porosity (94.3%), and shape memory performance with a shape recovery ratio of 96.7% and a shape fixity ratio of 98.6% under 50% compressive strain, outperforming previously reported PI aerogels. This work provided a feasible structural engineering strategy for developing high-performance PI aerogels that integrate large-strain shape memory functionality with structural stability, holding significant promise for thermal management in harsh, space-constrained environments, such as aerospace engineering.