Construction of Silica/Polyurethane/Epoxidised Natural Rubber Vitrimer Biobased Elastomers via Octa-Hydrogen Bonding with Interfacial β-Hydroxy Ester Bonding

Developing biobased rubber composites that simultaneously boost tensile strength and elongation at break while integrating self-healing capacity and reprocessability remains a critical challenge in the rubber industry. Inspired by the unique multiple hydrogen bonding structure of spider silk and the dynamic β-hydroxy ester exchange reaction, this study constructed an epoxy polyurethane rubber containing octuple hydrogen bonds and incorporated it into epoxidized natural rubber. Carboxylated silica was utilized as a bridging agent to form β-hydroxy ester reversible covalent bonds at the interface between the filler and the rubber, thereby designing a high-strength, self-repairing, and reprocessable’vitrimer’ biobased elastomer. This design approach endows the material with outstanding mechanical properties (tensile strength of 8.92 MPa, Young’s modulus of 2.71 MPa, toughness of 17.45 MJ/m3), excellent self-healing performance (healing efficiency of 92.1%), and superior processability (tensile strength recovery of 97.6%). These properties are primarily attributed to the presence of reversible noncovalent octet hydrogen bonds and dynamic covalent β-hydroxy ester bonds. Furthermore, this design can be readily implemented across different biobased epoxy polymers and carboxyl-rich nanofillers. The design concepts presented herein can be applied to the development of self-healing and reprocessable’vitrimer’ biobased elastomers, providing valuable insights for the future design of green and sustainable polymers.