Improved polymerization and depolymerization kinetics of poly(ethylene terephthalate) by co-polymerization with 2,5-furandicarboxylic acid

Poly(ethylene terephthalate) (PET), known for its clarity, food safety, toughness, and barrier properties, is a preferred polymer for rigid packaging applications. PET is also one of the most recycled polymers worldwide. In light of climate change, significant efforts are underway to improve the carbon footprint of PET by synthesizing it from bio-based feedstocks. Often times, specific applications demand PET to be copolymerized with other monomers. This work focuses on copolymerization of PET with a bio-based co-monomer, 2,5-furandicarboxylic acid (FDCA) to produce the copolyester (PETF). We report the multifunction of FDCA to influence the esterification reaction kinetics and the depolymerization kinetics (via alkaline hydrolysis) of the copolyester PETF. NMR spectroscopy and titrimetric studies revealed that copolymerization of PET with different levels of FDCA improved the esterification reaction kinetics by enhancing the solubility of monomers. During the alkaline hydrolysis, the presence of FDCA units in the backbone almost doubled the PET conversion and monomer yield. Based on these findings, it is demonstrated that the FDCA facilitates the esterification, as well as depolymerization of PET, and potentially enables reduction of reaction temperatures or shortened reaction times to improve the carbon footprint of the PET synthesis and depolymerization process.