Shape memory polyimides and composites with tunable chain stiffness and ultrahigh transition temperature range

Shape memory polymer has shape morphing capabilities upon external stimuli, including thermal-, electro-, magnetic-, photo-, and so on. Among them, shape memory polyimide (SMPI) has excellent thermal stability, creep resistance, radiation resistance, and good mechanical properties, which can be applied in various fields. In this paper, 5-amino-2-(4-aminophenyl) benzimidazole, 2-(4-aminophenyl) benzoxazol-5-amine, and 3,3′,4,4′-biphenyltetracarboxylic dianhydride are utilized to synthesize two semi-trapezoidal aromatic heterocyclic SMPIs with tunable chain stiffness, including imidazole-based shape memory polyimide (M-SMPI) and oxazole-based shape memory polyimide (E-SMPI). Because of asymmetric imidazole groups, M-SMPI has the highest SMPI transition temperature in the world, at 416 ℃. Additionally, the M-SMPI/CF composite also has the highest SMPIC (shape memory polyimide composite) transition temperature, at 399 ℃. Thus, M-SMPI and M-SMPI/CF composites can be used as smart materials in deformable flexible electrodes, high temperature aerospace devices and deployable structures.