Healable and recyclable supramolecular poly(urethane-urea) elastomers with high mechanical robustness, low hysteresis, fatigue resistance and antibacterial based on dynamic double crosslinked networks

Abstract

Polyurethane elastomers, characterized by their exceptional mechanical properties, self-healing capabilities, recyclability, and multifunctionality, have found extensive applications in the fields of tissue engineering, medical health, and flexible electronics. However, attaining mechanical robustness, low hysteresis, fatigue resistance, self-healing, and recyclability through existing network structures presents a significant challenge. In this study, a supramolecular poly(urethane-urea) elastomer featuring a double crosslinked network with dual dynamic bonds is developed by incorporating imidazolidinyl urea (IU) as a multiple hydrogen-bonding motif and dynamic disulfide bonds into supramolecular networks. Owing to this structural feature design strategy, the supramolecular poly(urethane-urea) elastomer exhibits remarkable properties, including high strength (50.8 MPa), ultrahigh toughness (932 MJ/m3), excellent fracture energy (195.6 kJ/m2), low hysteresis (10.8 %), and outstanding anti-fatigue properties, as evidenced by cyclic tensile testing. Furthermore, the dynamic disulfide bond and reversible hydrogen bonding dual networks bestow the elastomers with favorable self-healing properties and recyclability. Additionally, due to the synergistic effect of IU and elemental S, the polymer film also demonstrates excellent antibacterial properties against Gram-positive Staphylococcus albus and Gram-negative Escherichia coli, while maintaining low toxicity to mouse fibroblast cells (L929). Moreover, the fabricated sensor exhibits long-term stability and can sensitively detect the bending motion of human joints, attributable to the stable double crosslinked networks. This study showcases the design of self-healing and recyclable polyurethane elastomers with high mechanical robustness, low hysteresis, fatigue resistance, and antibacterial properties, thereby providing a novel approach for the development of medical and electronic materials in the future.