Low-temperature alcoholysis as a strategy for polyethylene terephthalate recycling and upcycling.

Postconsumer plastic waste has the potential to serve as a valuable feedstock in an integrated circular economy in which it can be interconverted between thermoplastic and thermoset materials. However, the development of cost-effective and sustainable recycling or upcycling methods is often constrained by harsh reaction conditions, limited catalyst performance, and overall low process efficiency. Here, we report the low-temperature (120°C) alcoholysis of polyethylene terephthalate (PET) that allows the application of functional, bioderivable alcohols in the depolymerization process. Terpenoids such as prenol proved highly effective, supporting both efficient depolymerization and repolymerization to PET. The unsaturated terpenolysis products were also used to prepare polymer networks via thiol-ene photochemistry and formulated into photocurable resins suitable for three-dimensional printing using digital light processing technology. The terpenoid-based networks were also able to be efficiently depolymerized, demonstrating the potential for loop-to-loop chemical recycling of PET/terpenoid materials. This work establishes low-temperature alcoholysis of PET as a practical strategy for advancing a broader circular PET-based materials economy.