Fabrication of shape memory polyimides with exploration of their activation mechanisms

The construction of polymer-based materials with reversible bidirectional shape memory effects, good thermal and electrically controlled properties is of paramount importance for the development of intelligent exploration in high-temperature fields. By adjusting the hydrogen bond contents of the structure to regulate the intermolecular strength, a series of random shape memory copolyimides have been synthesized with the triggering temperatures ranging from 275 to 384℃, which displayed good thermal stability, high shape fixation rate and shape recovery rate of over 95 % and 98 %, respectively, and excellent shape recovery speed (∼9 s). Visualized quantification of the microstructural phase evolution during stretching and the effects of hydrogen bonds on the properties of polyimide were deeply explored to better understanding the activation mechanisms of shape memory behaviors. Furthermore, flexible fabric composites with bidirectional shape memory effects motivated by electrical signals were also designed, providing a new sight of exploration for high-temperature shape-memory materials.