Metathesis of butadiene rubber for the sustainable production of polyesters and polyols

Synthetic rubbers and elastomers are used extensively in different industries today, and more than 11.8 million tons are consumed annually. Butadiene rubber (BR) is the second most important synthetic rubber, with a worldwide consumption of about 3.44 million tons annually. In response to the high demand, production, and waste of BR and other industrial rubbers, a global effort has been made to reduce elastomeric, plastic, and microplastic pollution by studying various mechanisms of polymer degradation, including thermal degradation, mechanical treatment, UV exposure, and chemical processes. This work reported the synthesis of polyesters and polyols via metathesis degradation reaction from BR using the fatty acid methyl 10-undecenoate and the fatty alcohol 10-undecen-1-ol as chain transfer agents (CTA), using mild reaction conditions and a Ru catalyst. Polyesters and polyols were successfully produced with 94-97% yield. The formation of polyol, polyester, and by-products was assessed by FT-IR, NMR, GC/MS, and TGA. The molecular weights (Mn, Mw, Mz, and PDI) before and after degradation of BR and the products obtained were characterized by GPC. Different mole ratios BR:CTA were used to control the molecular weights; the Mw obtained ranged from 395 to 3963 Da. The proposed metathesis route may contribute to the reuse and recycling of BR to obtain sustainable products with added value for the synthesis of new materials.