4D Printed Shape Memory Polyimide Composite Aerogels with High Recovery Stress for Load Driving

Shape memory polyimide aerogels with lightweight, high-temperature resistance, and excellent shape memory performance are ideal materials for intelligent structural components of aerospace. However, their low recovery stress has been a significant barrier to their practical use, particularly in driving structural deformations. Herein, we have prepared a 4D printed shape memory polyimide/polyimide nanofiber (PI/PIF) composite aerogel with high recovery stress and excellent shape memory performance for load driving at high temperatures. The PIF enhances ink printability and mechanical properties, allowing for the design of PI/PIF aerogels with double-curve macrostructures by 3D printing technology. During the shape programming process, double-curve macrostructures can absorb elastic strain energy to enhance recovery stress. Consequently, the printed PI/PIF aerogels exhibit a low density (0.09 g cm^-3) and a high specific recovery stress (2.8 N mm kg^-1) and can drive the deformation of 10 times their own weight. The proposed aerogel is expected to expand the application of lightweight shape memory materials for driving components in aerospace.