Self-healing polyurethane with high strength and toughness based on a dynamic chemical strategy

Abstract

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.