Six years ago, Ludwik Leibler and colleagues developed a new type of plastic with some impressive properties: It was tough like a thermoset polymer, such as Bakelite, but malleable like glass in that it could be melted and its shape reset. Leibler, of France’s National Center for Scientific Research, called the new material a vitrimer. The key to the vitrimer’s malleability was its chemistry. It consisted of ester cross-links that could break and reconnect with new partners when heated. Looking to apply this concept to polymers more commonly in use, Leibler, Renaud Nicolaÿ of the City of Paris Industrial Physics & Chemistry Higher Educational Institution, and colleagues have now switched out the ester cross-links for dioxaboralane cross-links (shown). These functional groups can be incorporated into commonly used polymers, such as poly(methyl methacrylate), polystyrene, and high-density polyethylene. When heated to 60 °C, the dioxaboralanes undergo metathesis—that is, they swap binding partners. The new vitrimers are also amenable to commercial processing methods, Leibler told attendees at the ACS meeting. The vitrimers could be processed, ground, and reprocessed several times via extrusion, compression molding, or injection molding, just like commercial thermoplastics. The research was also reported in Science (2017, DOI: 10.1126/science.aah5281).