Constructing mechanically robust and self-repairable ENR/PP vitrimer composites via interfacial β-hydroxy ester bonding with silica nanofillers

Thermally repairable elastomers combining high mechanical properties and efficient self-healing capability remain challenging due to the inherent property conflicts. In this work, an epoxidized natural rubber (ENR)-based vitrimer composite was successfully developed by constructing a hybrid dynamic network through sebacic acid crosslinking of ENR combined with interfacial β-hydroxy ester bond formation using KH560 functionalized SiO 2 (KSiO 2 ), where the functionalized silica simultaneously acts as reinforcing filler and dynamic crosslinker. Moreover, polypropylene (PP) was incorporated to enhance the mechanical performance of the elastomeric matrix. With increasing KSiO 2 content, the composites achieved 34.1% higher tensile strength and 44.6% greater elongation at break, while the PP incorporated composites yielded superior tensile strength compared to the unfilled composites. Furthermore, the composites demonstrated complete incision recovery under thermal treatment, and retained more than 90% of original tensile strength after healing.