Upcycling Commodity Plastics toward Reversible Smart Responsive Materials through Dynamic Crosslinking

Plastics have become an indispensable part of our daily life, but the management of their waste presents a global challenge. Plastic upcycling can be an alternative way to address challenges related to waste plastics and property degradation of current recycling methods. Adaptive polymeric materials through dynamic (reversible) bonds have the potential unique properties to create various revolutionary future technologies. Dynamic bonds can selectively undergo reversible bond breaking and reformation in specific conditions that enable structural rearrangements in polymer networks, strongly improve the toughness, and provide recyclability, self-heal ability, as well as smart response behavior. In contrast, permanently crosslinked polymers (e.g. thermosets), which comprise 15-20% of all produced polymers, are not able to show those dynamic features due to their unpliable nature. Incorporating dynamic covalent bonds into a crosslinked polymeric network provides outstanding mechanical properties due to their crosslinked nature and malleability, thus repeated recyclability. In a recent study we upcycled a commodity thermoplastic elastomer, polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) toward higher value materials. The incorporation of dynamic covalent and noncovalent bonds into the polymer and the interface enable mechanically robust, processable, and smart responsive thermoset materials, where bonding and debonding at the interfaces dictate smart response behavior. Crosslinking with fast-exchangeable boronic ester showed enhanced malleability, reprocessability, and healability upon heating. This crosslinked polymer also exhibits excellent chemical, and thermal stability, and reversible smart responses such as stretch-induced reversible transparency. This presentation will discuss the design, synthesis, recycling, and mechanistic investigation of stretch-induced reversible smart responses of SEBS-based-novel dynamic crosslinked polymers.