Design of a dual dynamic elastomeric vitrimer based on disulfide metathesis and transesterification reactions

Abstract

Vitrimers represent a promising class of new-generation materials with covalent adaptive networks (CANs) based on an associative exchange mechanism. Herein, we utilised epoxy-functionalized elastomers, like poly(ethylene-co-vinyl acetate-co-glycidyl methacrylate) (EVA-GMA), for designing a dual dynamic network based on β-hydroxyl ester linkage as well as disulfide metathesis reactions, which were enabled by a new crosslinker, succinic anhydride-modified 4-aminophenyl disulfide (SA-APDS), which has a disulfide linkage in the backbone and a –COOH group at the para position. These dynamic linkages are capable of undergoing exchange reactions at elevated temperatures, thereby allowing the rearrangement of the network topology and exhibiting vitrimer-like behaviour. The resultant elastomeric vitrimer exhibits good mechanical performance, including a tensile strength of ∼6.1 MPa and elongation at break up to 1300%, demonstrating super-elastomeric characteristics. Interestingly, the elastomeric vitrimer showed fluorescence behaviour due to the presence of a conjugated system in the new crosslinker. The ability of this material to maintain and reconfigure crosslink density through dual associative mechanisms showed that vitrimer-like materials have self-healing, recyclable, and reprocessable characteristics. Stress relaxation experiments confirmed the vitrimeric behaviour with an activation energy of 46.8 kJ mol⁻¹ and a vitrification temperature of 83 °C. This new vitrimeric elastomer, with fluorescence characteristics, can have potential applications in areas where a unique combination of mechanical and optical properties is necessary.