Synergistic integration of dynamic acylsemicarbazide bonds and disulfide bonds into polyurethane: A facile strategy to surmount the tradeoff between mechanical strength and self-healing capacity of elastomers

The polymeric materials can simultaneously possess high mechanical properties and outstanding self-healing performance under mild condition have found widespread applications in various fields. However, this type of polymers is exceedingly rare due to the trade-off between mechanical robustness and chain flexibility for healing. In this study, we designed a facile strategy for synergistic integration of dynamic acylsemicarbazide (ASC) bonds and disulfide bonds into polyurethane elastomer by the reaction between 3,3′-dithiobis(propionohydrazide) and isocyanate-terminated Pre-PU. The obtained elastomer ASC-SS-PU not only possesses an outstanding tensile strength (17.1 MPa), good stretchability (735%) and high toughness (57.16 MJ·m⁻³), but also exhibits excellent self-healing performance under mild condition. The healing efficiency of the damaged ASC-SS-PU samples (breakage rate >90%) can reach over 70% healing at 60°C for 40 min, which is much lower than conventional ASC-based PU elastomer. Considering the simple and easy-to-scaleup preparation process and commercially available low-cost raw materials, outstanding mechanical strength and toughness, as well as high healing efficiency under mild condition, the ASC-SS-PU elastomer as self-healing but strong materials have great potential for use in various fields.