The Evaluation of Eutectic Solvents as Catalysts for Mediating the Greener Synthesis of Poly(alkylene 2,5-furandicarboxylate)s

In a quest to develop more sustainable polymers, decoupling their production from fuel-based resources and searching for alternative greener synthetic pathways are important priorities. Among the numerous polymers that fall into this category are furan-based polyesters. Besides the origin of polymers, their synthesis is another critical topic to consider regarding the overall greenness of the final product. However, despite several studies focusing on bio-based alternatives, such as poly(alkylene 2,5-furandicarboxylate)s, their synthesis still relies on air- and water-sensitive metal-based catalysts and is typically carried out under harsh conditions. This study explores an alternative approach with the application of eutectic solvents (ES) as catalysts for a more sustainable approach for synthesising furan-based polyesters, specifically poly(ethylene 2,5-furandicarboxylate) (PEF), as well as poly(trimethylene furandicarboxylate) (PTF) and poly(butylene furandicarboxylate) (PBF). Two different ES were evaluated as catalysts; the best results were obtained with urea and zinc acetate ES (U:Zn(OAc)₂, 4:1 mol:mol). The resulting polymers were analysed for their structure, molecular weight, and thermal properties.