DFT study on the depolymerization of PET by Ca-catalyzed glycolysis reaction model
Anyarin Arunphacharawit, Thinnaphat Poonsawat, Titiya Meechai, Laksamee Chaicharoenwimolkul Chuaitammakit, Ekasith Somsook
Abstract
Poly(ethylene terephthalate) (PET) is the most common plastics produced for applications in food and drinking containers. It is degraded to valuable product by several methods. Glycolysis of PET gains bis(2-hydroxyethylene) terephthalate (BHET) as the main product utilized as plasticizer. Calcium catalysts, Ca2+ and Ca(OH)2∙2H2O were explored to study the mechanism of PET cleavage by DFT calculations at B3LYP/6-311++G** level. Two possible pathways, coordination, and non-coordination of ethylene glycol on the calcium in glycolysis reaction, have been investigated. In addition, poly(ethylene furanoate) (PEF), considered as a sustainable polymer with the similar functional properties, was chose for the comparison of conformational structures with PET. The understanding of the relationship between PET (and PEF) structures and calcium catalysts is useful for the future development of linear sustainable polyesters.