A crown-ether-based polyurethane with enhanced energy dissipation via sacrificing host-guest complex structures

Elastomers find extensive applications across industries and daily life owing to their superior mechanical properties. However, the development of high-toughness elastomers through innovative methods remains a significant scientific challenge, necessitating the design of sophisticated structures for efficient energy dissipation. In this study, we introduce a novel crown-ether-based sacrificial structure that enhances energy dissipation through conformational changes. A series of polyurethane elastomers, denoted as PU-C_xI_y, were synthesized using a Schiff base-based crown ether (SBCE) and isophthalic dihydrazide (IPDH) as the chain extender. The results demonstrated that the tensile strength of PU-C_xI_y can reach as high as 46.8 ± 0.8 MPa and toughness can reach 248.1 ± 5.9 MJ/m³. In addition, the introduction of crown ether ring caused an increase in the energy dissipation of the elastomer by more than two times. Meanwhile, further improvements in energy dissipation were observed upon the incorporation of potassium ions (referred to as PU-C_xI_y-K⁺). This enhancement was attributed to the additional energy dissipation resulting from the detachment of potassium ions from the crown ether rings during force-induced conformational changes in the complex structures. Notably, the energy dissipation reached its maximum at moderate crown ether contents, highlighting the critical role of noncovalently crosslinked networks. This study provides new insights and strategies for designing elastomers with superior performance.