Tailoring Microphase Separation via Host–Guest Stoichiometry in Supramolecular Polyurethanes for Ultratoughening and Self-Healing

Balancing mechanical strength and self-healing capability remains a significant challenge in the development of high-performance elastomers. Although microphase separation and dynamic sacrificial bonds have proven effective in overcoming this limitation, precise control over the degree and morphology of microphase separation continues to present substantial difficulties. In this study, we designed a robust supramolecular polyurethane (PU) elastomer by synergistically incorporating multiple hydrogen bonds and host–guest interactions, resulting in a supramolecular network that exhibits both ultrahigh mechanical properties and efficient self-healing. By systematically modulating the stoichiometric ratio of β-cyclodextrin (β-CD) to ferrocene (Fc) units, we achieved a tailored microphase separation state within the elastomeric matrix. The optimized material demonstrates exceptional mechanical performance with a tensile strength of 53.7 MPa, a toughness of 337.6 MJ/m3, and a fracture energy of 126.4 kJ/m2. Furthermore, the elastomer retains approximately 70% of its original toughness after multiple reprocessing cycles, which indicates good self-healing efficiency and recyclability. This work provides valuable insights into the molecular-level design of supramolecular elastomers and significantly enhances their potential for practical applications requiring durability and sustainability.