Upcycling of Vulcanized Rubber via Controlled Backbone Cleavage and Functionalization. | CU Experts

Vulcanized rubbers, essential in tires and many other elastomers, are exceptionally difficult to recycle because their sulfur-cross-linked, additive-rich networks resist chemical degradation. This high resistance has created a mounting environmental burden, yet strategies that operate under mild and nontoxic-gas-emitting conditions while producing valuable products remain scarce. Here we report a mild, one-step oxidative approach that selectively cleaves backbone C═C bonds in both thermoplastic and vulcanized rubbers. By regulating the phase of an N-hydroxyphthalimide (NHPI)-based catalytic system, the process yields functionalized fragments with high terminal-group selectivity and tunable molar masses, following distinct degradation kinetics that afford tunable, time-independent molar masses. These chemically functionalized fragments can be directly reused for applications such as 3D printing and adhesives or replace raw rubbers and plasticizers in tire tread formulations. This method has also been successfully applied to the recycling of real-life rubber waste, including tires and gloves, achieving >95% recovery, thus providing a practically useful and scalable route for chemical upcycling of highly inert polymer waste.

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