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

Abstract

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 ∼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 CO2e kg-1), while chemical recycling emits only 2 kg CO2e kg-1. This cost and emissions disparity provides a strong incentive to recover and recycle future polymer waste.