The introduction of disulfide bonds in polyurethane elastomers confers self-healing and recyclable properties to the elastomers, which not only reduce the maintenance cost but also prolong the service life. However, the mechanical properties of such elastomers with good healableity are frequently poor, and the development of polyurethane elastomers with high self-healing rates as well as high toughness and stiffness still remains a significant challenge. Herein, the preparation of polyurethane elastomers using 1,8-menthane diamine (MD) and bis(2-hydroxyethyl)disulfide (HEDS) as chain extenders is reported. MD amino groups and isocyanate react to form H-bonded urea groups, offering improved mechanical properties, while the rigid ring structure of MD promotes the decomposition of disulfide bonds. The MD-PU-SS elastomer has a tensile strength of 24.8 MPa. The toughness and fracture energy of MD-PU-SS were found to be 274.6 MJ m⁻³ and 114.43 kJ m⁻², respectively. The introduction of MD allows MD-PU-SS to not only maintain good mechanical properties but also have up to 94% healing efficiency and good recyclability. This study provides a new path for the design and fabrication of healable polyurethane elastomers with high toughness and crack tolerance, and we present herein the synthesis and testing of one such high-performance polymer.

The thiosemicarbazone derivatives have a wide range of biological activities, such as antioxidant activity. In this study, the antiradical activities of six camphene-based thiosemicarbazones (TSC-1~6) were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and peroxyl radical scavenging capacity (PSC) assays, respectively, and the results reveal that TSC1~6 exhibited good abilities for scavenging free radicals in a dose-dependent way. Compound TSC-2 exhibited the best effect of scavenging DPPH radical, with the lowest EC₅₀ (0.208 ± 0.004 mol/mol DPPH) as well as the highest bimolecular rate constant K_b (4218 M⁻¹ s⁻¹), which is 1.18-fold higher than that of Trolox. Meanwhile, TSC-2 also obtained the lowest EC₅₀ (1.27 µmol of Trolox equiv/µmol) of scavenging peroxyl radical. Furthermore, the density functional theory (DFT) calculation was carried out to further explain the experimental results by calculating several molecular descriptors associated with radical scavenging activity. These theoretical data suggested that the electron-donating effect of the diethylamino group in TSC-2 leads to the enhancement of the scavenging activities and the studied compounds may prefer to undergo the hydrogen atom transfer process.