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

Abstract

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 ≈ 8−33 MPa, elongation at break ≈ 345−680%, and Young's modulus ≈ 19−270 MPa). The samples displayed typical vitrimer behavior and stress relaxed in the temperature range of 140 to 180 °C. The PUNs, thermally reprocessed at 150 °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 °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.

Robust Catechol Containing Cationic Waterborne Polyurethanes with Antibacterial, UV Protective, and Adhesive Properties

“…However, the tensile strength first increases and then decreases significantly with a maximum strength of 43 MPa (CWPU‐2), similarly to the toughness trend (Figure S2, Supporting Information). The mechanical properties of the CWPUs exceed the records of solvent‐based polyurethane, [ 41,42 ] anionic WPU, [ 43,44 ] and similar CWPUs [ 32,45,46 ] reported in the literature (Figure 3d). The reason for the result tendency is that the catechol structure in neutralizers DBA can be a donor or acceptor of the hydrogen bond and form cation– π interactions to optimize dense molecular crosslinking networks and the physical interaction force contributed to the energy dissipation when subjecting to external forces.…”

Facile in situ construction of a covalent adaptable network polyester vitrimer with advanced performance in repairability, foamability and recyclability

“…The reason is that the 0.8 BT sample has covalent adaptable networks, enabling a fast exchange reaction of transesterification. 38 The synergistic catalyst effect of excess hydroxyl groups, 39 NGP, and the tertiary amine structure endowed the covalent adaptable networks with an extremely fast transesterification rate, leading to the fast self-healing behavior. Interestingly, the field of view in POM is affected by crystallization.…”

A dynamic polyurea network with exceptional creep resistance

“…23 Much efforts have been made to suppress the deformation (creep) of CANs while maintaining their reprocessability. One strategy is to incorporate a certain amount of permanent crosslinks into CANs, 24,25 and the limiting ratio is about 50 mol% according to Torkelson's report. 26 However, this strategy not only impairs the reprocessability but also cannot completely restrain the deformation.…”