A hindered-urea vitrimer: recyclable for circular use and upcyclable for rechargeable batteries†

Abstract

The matter cycle and renewable energy are fundamental to sustainable development. Despite the recognized urgency of plastic recycling, its implementation remains technologically limited. A dynamic crosslinker can enable a thermoset to exhibit thermoplastic-like reprocessability under elevated conditions, such as elevated temperatures or stress, paving the way for plastic recovery while retaining thermoset properties under normal operational conditions. This study incorporated a hindered urea linkage as the dynamic crosslinker into a commodity plastic to produce a recyclable thermoset. The polymer demonstrated excellent reprocessability under elevated conditions while maintaining its thermoset characteristics under normal working conditions. Furthermore, considering the inevitability of some eventually discarded polymers, the upcycling of polymer waste was demonstrated to produce an advanced carbon for potassium-ion batteries, which were found to be promising for grid-oriented energy storage for green power. With the assistance of zinc oxide during pyrolysis, the polymer-derived carbon showcased excellent performance and cost-effectiveness as an anode in the batteries. The dynamic hindered-urea vitrimer thus represents a holistic approach to both recycling and upcycling for a circular economy and renewable energy, respectively, towards sustainable development.