From waste to value: Scalable, one-pot upcycling of PET into high-performance copolyesters via hydroxy transesterification

Poly(ethylene terephthalate) (PET) accounts for 8 % of global plastic production and 12 % of solid waste, driving extensive research into innovative recycling strategies. Nonetheless, performance degradation of mechanical recycling and high cost of chemical routes, highlighting the urgent need for cost-effective PET recycling solutions. This study presents a “one-pot” upcycling approach based on hydroxy transesterification, which directly converts PET waste into high-performance copolyesters. A key advantage of this method is the elimination of solvents and the avoidance of complete depolymerization using excess ethylene glycol or methanol. Thermal and mechanical analyses reveal that upcycled poly(ethylene- co -1,4 cyclohexanedimethanol terephthalate) (PETG) exhibits properties comparable to commercial PETG. Furthermore, we successfully synthesized a series of heat-resistance copolyesters using various PET waste sources, rigid diols with varying reactivity (2,2,4,4-tetramethyl-1,3-cyclobutanediol, spiroglycol, and isosorbide)—demonstrating the broad applicability of this strategy. Techno-economic analysis (TEA) and life cycle assessment (LCA) demonstrate a 27.2 % reduction in production costs, along with 68 % and 84 % reductions in global warming potential and fossil fuel depletion, respectively. Overall, this platform provides a sustainable and cost-effective pathway for the upcycling of PET waste.