Multifunctional polyurethane elastomers with high mechanical robustness and exceptional crack tolerance performance based on bi-incompatible soft segments and dynamic coordination bonds

Abstract

Elastomers with high strength and super toughness are widely used in aerospace, flexible electronics, biomedical, and other fields. However, the development of healable and recyclable elastomers with high strength, high toughness, and excellent crack resistance remains a significant challenge. In this work, we successfully synthesized a multifunctional silicone-based elastomer (SiPUU-HPA@Fe) with outstanding mechanical properties, self-healing capabilities and recyclability by combining biocompatible polycarbonate (PCDL) segments, flexible polydimethylsiloxane (PDMS) segments and metal coordination bonds. Owing to the presence of phase separation structures and dynamic coordination interaction, the optimized SiPUU-HPA₂@Fe_1/3 elastomer exhibits a high tensile strength of 45.5 MPa, an ultrahigh toughness of 412.5 MJ m⁻³, and an exceptional fracture energy of 179.3 kJ m⁻². Additionally, the SiPUU-HPA₂@Fe_1/3 elastomers can be healed and recycled to regain their original mechanical strength and integrity under heating. Furthermore, the SiPUU-HPA₂@Fe_1/3 elastomer demonstrates excellent antibacterial properties and no cytotoxic effects. Finally, a soft SiPUU-HPA₂@Fe_1/3/Li based strain sensor was developed by combining SiPUU-HPA₂@Fe_1/3 with conductive ionic lithium bis(trifluoromethane)sulfonimide (LiTFSI) and demonstrated remarkable sensing capability to diverse human body motions. This research provides ideas for the design of polyurethane elastomers with high mechanical properties and multiple functions, and the elastomers are expected to be used in emerging fields such as biomedical and flexible electronics.