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Chemical Upcycling of Polyethylene to Value-Added α,ω-Divinyl-Functionalized Oligomers

2021; American Chemical Society; Volume: 9; Issue: 41 Linguagem: Inglês

10.1021/acssuschemeng.1c05272

2168-0485

Manhao Zeng, Yu‐Hsuan Lee, Garrett Strong, Anne M. LaPointe, Andrew L. Kocen, Zhiqiang Qu, Geoffrey W. Coates, Susannah L. Scott, Mahdi M. Abu‐Omar,

Recycling and Waste Management Techniques

Today, only 9% of plastic waste is recycled worldwide, with polyethylene being one of the most frequently discarded plastics. In this work, a new route to chemically recycle polyethylene is demonstrated. Polyethylenes of two different molecular weights (Mn = 1.5 kg/mol and Mn = 6.6 kg/mol) were upgraded to value-added α,ω-divinyl-functionalized oligomers with shorter, tunable chain lengths via a sequence of bromination, dehydrobromination, and olefin metathesis reactions. Brominated polyethylene (BPE) was isolated in good yields (up to 86 wt %, based on PE) by direct bromination of polyethylene in air, without oxidative cleavage side-reactions. Elimination of bromide resulted in complete conversion of BPE to vinylene polyethylene (VPE) in high yields (up to 91 wt %, based on BPE). Ethenolysis of VPE afforded α,ω-divinyl-functionalized oligomers, also in high yields (up to 97 wt %, based on VPE), with carbon numbers significantly lower than those of the starting PE. Preliminary techno-economic assessments demonstrate that this three-step process could be economically viable on an industrial scale for upcycling PE into value-added chemicals that can be used in the synthesis of lubricants, as well as transformed into new commodity polymers such as polyolefins, polyethers, polyesters, and polyamides.