Leveling the cost and carbon footprint of circular polymers that are chemically recycled to monomer

Mechanical recycling of polymers downgrades them such that they are unusable after a few cycles. Alternatively, chemical recycling to monomer offers a means to recover the embodied chemical feedstocks for remanufacturing. However, only a limited number of commodity polymers may be chemically recycled, and the processes remain resource intensive. We use systems analysis to quantify the costs and life-cycle carbon footprints of virgin and chemically recycled polydiketoenamines (PDKs), next-generation polymers that depolymerize under ambient conditions in strong acid. The cost of producing virgin PDK resin using unoptimized processes is similar to 30-fold higher than recycling them, and the cost of recycled PDK resin ($1.5 kg(-1)) is on par with PET and HDPE, and below that of polyurethanes. Virgin resin production is carbon intensive (86 kg CO(2)e kg(-1)), while chemical recycling emits only 2 kg CO(2)e kg(-1). This cost and emissions disparity provides a strong incentive to recover and recycle future polymer waste.

Automated summary

Mechanical recycling of polymers downgrades their usability, while chemical recycling offers a more sustainable way to recover chemical feedstocks. The cost and carbon footprint of chemically recycled PDKs are significantly lower than producing virgin resin, providing a strong incentive for recovering and recycling future polymer waste.