Dynamic Carboxylate Linkage Based Reprocessable and SelfHealable Segmented Polyurethane Vitrimers Displaying Creep Resistance Behavior and Triple Shape Memory Ability

Though conventional polyurethane foams are among the most widely used polymer materials currently, the lack of reprocessability and creep resistance ability restricts their further commercial growth. Imparting recyclability, self-healing, and creep resilience ability to segmented PU networks (PUNs) is desirable to further enhance their commercial utility and address the concern related to polymer waste accumulation. In this article, we utilize the strategy of incorporating a dynamic carboxylate linkage in the main chain of polytetramethylene oxide (PTMO)-based segmented PUNs to achieve the above. The resulting PUNs displayed adequate tensile properties (tensile strength similar to 8-33 MPa, elongation at break similar to 345-680%, and Young's modulus similar to 19-270 MPa). The samples displayed typical vitrimer behavior and stress relaxed in the temperature range of 140 to 180 degrees C. The PUNs, thermally reprocessed at 150 degrees C, recovered up to 70-85% of the original tensile strength. Importantly, these vitrimers displayed improved creep resistant behavior at elevated temperature, which has been a concern with the conventional vitrimer materials. The PUNs displayed triple shape memory abilities at inflection temperatures of 60 and 130 degrees C. The samples also exhibited effective self-healing and self-welding ability. Overall, these PUNs with versatile properties are potential candidates for a range of applications.