Researchers at the University of North Carolina at Chapel Hill have developed a chemical method for recycling rubber waste that addresses limitations in current recycling technologies.

The research team’s study, "Deconstruction of Rubber via C–H Amination and Aza-Cope Rearrangement," was published in Nature, and it introduces a novel chemical method for breaking down rubber waste. This technique utilizes C–H amination and a polymer rearrangement strategy to transform discarded rubber into valuable precursors for epoxy resins, offering an innovative and sustainable alternative to traditional recycling methods, according to a March 26 article on the UNC-Chapel Hill website.

Led by Dr. Aleksandr Zhukhovitskiy,  William R. Kenan, Jr. Fellow and assistant professor in the Department of Chemistry at UNC-Chapel Hill, the study introduces an approach to breaking down rubber's complex polymer structure, which has traditionally been challenging to recycle due to its durable cross-linked nature.

Traditional rubber recycling methods suffer from major drawbacks. Devulcanization weakens polymer mechanical properties, while other techniques produce low-value byproducts. This new method transforms rubber into valuable materials, specifically precursors for epoxy resins, through a two-step chemical process.

The researchers used a sulfur diimide reagent to strategically install amine groups in polymer chains, followed by a backbone rearrangement that breaks down the rubber. In laboratory tests, they demonstrated efficiency: a model polymer's molecular weight was reduced from 58,100 g/mol to approximately 400 g/mol, and used rubber was completely transformed into a soluble material within six hours.

Notably, the process operates under mild conditions (35–50°C) in aqueous media, making it more environmentally friendly and cost-effective than existing methods. The resulting amine-modified materials can create epoxy resins with strengths comparable to commercial products, offering an alternative to petroleum-based manufacturing.