Catalyst free PET and PEF polyesters using a new traceless oxalate chain extender

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Polymers

Background:

• Polymer molecular weight is critical for material performance, especially for polyesters like PET and PEF.
• Achieving high molecular weights often requires metal catalysts (e.g., antimony, tin) and lengthy processes.
• Incorporating bio-based comonomers like isosorbide (e.g., PEIF) further complicates achieving high molecular weights.

Purpose of the Study:

• To present a new, easily implementable method for producing high molecular weight PET, PEF, and their isosorbide-containing copolymers (PEIT, PEIF).
• To demonstrate the use of diguaiacyl oxalate (DGO) as a metal-free chain extender.
• To address sustainability and ecological concerns associated with metal catalysts in polyester production.

Main Methods:

• Utilized diguaiacyl oxalate (DGO) as a reactive chain extender to couple lower molecular weight polymer chains.
• Applied DGO to polyethylene terephthalate (PET), polyethylene furanoate (PEF), and their isosorbide copolyesters (PEIT, PEIF).
• Investigated the complete removal of DGO from the final polymer products.

Main Results:

• Successfully produced high molecular weight PET, PEF, PEIT, and PEIF without metal catalysts.
• DGO's high reactivity enabled efficient chain coupling, avoiding the need for additional solid-state polymerization steps.
• Demonstrated that DGO can be completely removed from the polymer, unlike conventional chain extenders.

Conclusions:

• DGO offers a sustainable and efficient alternative for synthesizing high molecular weight polyesters and copolyesters.
• The metal-free approach using DGO mitigates environmental concerns associated with traditional catalysts.
• The ability to remove DGO completely offers a significant advantage over existing chain extension methods.