Elastic vitrimers: Beyond thermoplastic and thermoset elastomers

Thermoset elastomers are widely used in industry and frontier research due to their advantage of mechanical robustness, high thermal/chemical resistance, and good dimensional stability. How-ever, the presence of permanent crosslinks in thermoset elastomers significantly limits their recyclability. Polymer networks with asso-ciative exchangeable crosslinkers, called vitrimers, are reported to provide a path to polymer circularity for traditional thermosets. Herein, we provide a review of representative studies dedicated to the design, synthesis, fundamental physics, and property evalua-tion of elastic vitrimers that are synthesized based on different types of dynamic covalent bonds. Control on the network parame-ters (e.g., type of chemical bond, crosslink density, polymer back -bone, and network architecture) of the elastic vitrimers enables them to tailor their mechanical performance, network dynamics, self-healing capability, and recyclability. The dynamic nature of reversible chemical bonds allows controlling the responsive behavior of elastic vitrimers to a variety of external stimuli, such as temperature, light, and moisture. Special attention is paid to the critical physical parameters in elastic vitrimers, such as topology freezing temperature (T-v), and their comparison with those of widely used thermoset and thermoplastic elastomers. The merits, bottle-necks, and future research directions of elastic vitrimers are also discussed toward their practical applications in various fields.