Multiple/Two‐Way Shape Memory Poly(urethane‐urea‐amide) Elastomers

Multiple and two‐way reversible shape memory polymers (M/2W‐SMPs) are highly promising for many fields due to large deformation, lightweight, strong recovery stress, and fast response rates. Herein, a semi‐crystalline block poly(urethane‐urea‐amide) elastomers (PUUAs) are prepared by the copolymerization of isocyanate‐terminated polyurethane (OPU) and amino‐terminated oligomeric polyamide‐1212 (OPA). PUUAs, composed of OPA as stationary phase and PTMEG as reversible phase, exhibit excellent rigidity, flexibility, and resilience, and cPUUA‐C7‐S25 exhibits the best tensile property with strength of 10.3 MPa and elongation at break of 360.2%. Besides, all the PUUAs possess two crystallization/melting temperatures and a glass transition temperature, which endow PUUAs with multiple and reversible two‐way shape memory effect (M/2W‐SME). Physically crosslinked PUUA‐C0‐S25 exhibits excellent dual and triple shape memory, and micro chemically crosslinked cPUUA‐C7‐S25 further shows quadruple shape memory behavior. Additionally, both PUUA‐C0‐S25 and cPUUA‐C7‐S25 have 2W‐SME. Intriguingly, cPUUA‐C7‐S25 can achieve a higher temperature (up to 165 °C) SME, which makes it suitable for more complex and changeable applications. Based on the advantages of M/2W‐SME, a temperature‐responsive application scenario where PUUAs can transform spontaneously among different shapes is designed. These unique M/2W‐SME and high‐temperature SME will enable the applications of high‐temperature sensors, actuators, and aerospace equipment. A semi‐crystalline block poly(urethane‐urea‐amide) elastomers (PUUAs) are prepared by the copolymerization of isocyanate‐terminated polyurethane and amino‐terminated oligomeric polyamide‐1212. Intriguingly, PUUAs with multiple, reversible two‐way and high‐temperature shape memory effect make them suitable for more complex and changeable applications. These unique M/2W‐SME and high‐temperature SME will enable the applications of high temperature sensors, actuators, and aerospace equipment.