Chemical recycling of waste plastics for new materials production

Abstract

Once referred to as ‘materials of 1,000 uses’, plastics meet demands in everything from clothing and automotive sectors to the manufacturing of medical equipment and electronics. Concomitant with usage, worldwide generation of plastic solid waste increases daily and is currently around 150 million tonnes per annum. Although recycled materials may have physical properties similar to those of virgin plastics, the resulting monetary savings are limited and the properties of most plastics are significantly compromised after a number of processing cycles. An alternative approach to processing plastic solid waste is chemical recycling, the success of which relies on the affordability of processes and the efficiency of catalysts. In this Review, we describe technologies available for sorting and recycling plastic solid waste into feedstocks, as well as state-of-the-art techniques to chemically recycle commercial plastics. These evaluations are followed by a survey of recent advances in the design of new high-performing recyclable polymers.

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Figure 1: The prices of virgin SPI code 1–6 plastics in the United States between 2002 and 2017.
Figure 2: Depolymerization of waste PET can afford a range of useful monomers.
Figure 3: Depolymerization of polyethylene.
Figure 4: Depolymerization of poly(bisphenol A carbonate).
Figure 5: Dynamic covalent materials can undergo topological rearrangements while still maintaining their network integrity.
Figure 6: Steric strain at urea linkers enables hydrolysis of tunable polyurea networks.

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Acknowledgements

The authors thank C. H. Fox for insights and discussions.

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Correspondence to Jeannette M. García.

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Rahimi, A., García, J. Chemical recycling of waste plastics for new materials production. Nat Rev Chem 1, 0046 (2017). https://doi.org/10.1038/s41570-017-0046

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