Single-use plastics are now ubiquitous in consumer and industrial products due to their low cost, light weight, durability, and high stability. However, these omnipresent commodity polymers are often resistant to environmental degradation. Recent data indicates that the majority of waste plastics end up in either landfills or the environment, with less than 10% recycled. Closed-loop recycling offers the opportunity to help mitigate this plastic waste through reversible polymer construction and deconstruction. While examples of the chemical recycling polymers are known, few have been applied to materials derived from abundant commodity olefinic monomers that are the building blocks of ubiquitous plastic resins. Here we describe an iron-catalyzed [2+2] cycloaddition oligomerization of 1,3-butadiene to yield a previously unrealized polybutadiene; this new material has a telechelic microstructure of linked cyclobutyl groups in the form of (1,n’-divinyl)oligocyclobutane. The polymer is thermally stable, has stereoregular segments arising from chain-end control, and exhibits high crystallinity even at low molecular weight. Exposure of the oligocyclobutane to vacuum in the presence of the iron precatalyst used to synthesize it resulted in depolymerization to generate pristine butadiene, demonstrating a rare example of closed-loop chemical recycling of an oligomeric material derived from a commodity hydrocarbon feedstock.

Iron catalyzed synthesis and chemical recycling of telechelic, 1,3-enchained oligocyclobutanes

ACS Spring Meeting 2021

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