DFT study on the depolymerization of PET by Ca-catalyzed glycolysis reaction model

Area of Science:

• Polymer Chemistry
• Materials Science
• Computational Chemistry

Background:

• Poly(ethylene terephthalate) (PET) is a widely used plastic for food and drink containers.
• PET degradation yields valuable products, such as bis(2-hydroxyethylene) terephthalate (BHET), a plasticizer.
• Sustainable alternatives like poly(ethylene furanoate) (PEF) are being developed.

Purpose of the Study:

• To investigate the mechanism of PET cleavage using calcium catalysts (Ca2+ and Ca(OH)2·2H2O).
• To compare the conformational structures of PET and PEF.
• To provide insights for developing sustainable linear polyesters.

Main Methods:

• Density Functional Theory (DFT) calculations at the B3LYP/6-311++G** level were employed.
• Two reaction pathways (coordination and non-coordination) of ethylene glycol on calcium were analyzed.
• Conformational structures of PET and PEF were compared.

Main Results:

• The study elucidated the mechanism of PET glycolysis catalyzed by calcium.
• Both coordination and non-coordination pathways of ethylene glycol on calcium were investigated.
• Conformational differences between PET and PEF were analyzed.

Conclusions:

• Understanding the interaction between PET/PEF structures and calcium catalysts is crucial.
• This research contributes to the development of efficient and sustainable polyester recycling methods.
• The findings support the advancement of eco-friendly polymer technologies.