An Introduction of Ultrahigh-Molecular-Weight Poly(tetramethyl glycolide) (PTMG): Mechanically Strong and Completely Recyclable

Bio-based polymers are essential for attaining a sustainable circular plastic economy. Poly(l-lactic acid) (PLLA) provides a sustainable alternative to synthetic polymers, but its high gas permeability and moderate strength limit its applications. Poly(tetramethyl glycolide) (PTMG) shows promise as a sustainable polymer to PLLA but has inadequate tensile strength due to its low molecular weight produced by current uncontrolled anionic ring-opening polymerization methods. In order to combat this, researchers at Dalian University of Technology, China, have developed a completely recyclable and high-strength Ultrahigh-Molecular-Weight PTMG polymer.

About PTMG

Polytetramethylene glycol (PTMG), also known as polytetrahydrofuran (PTHF), is a linear polyether polymer widely used as a soft, flexible segment in polyurethane elastomers, thermoplastic elastomers, and copolyesters. Due to its exceptional elasticity, low glass transition temperature, and great flexibility, PTMG is highly desired in applications including industrial belts, spandex fibers, and elastomeric films that demand resilience under dynamic stress.

Graphical abstract showing synthesis of ultrahigh-molecular-weight PTMG (Source: ACS)

Synthesis and results of ultrahigh-molecular-weight PTMG

Here, tetramethyl glycolide (TMG) monomer, obtained from a renewable resource, in the presence of an organic catalyst, was synthesized to ultrahigh-molecular-weight (Mn up to 1139 kg mol–1) metal-free PTMG. The developed polymer had enhanced tensile strength and modulus of 80.0 MPa and 4.9 GPa, respectively. Furthermore, the polymer exhibited enhanced gas barrier and transparency properties in comparison to PLLA (Mn = 58.6 kg mol–1). Lastly, the polymer could also be depolymerized to completely recover the TMG monomer utilizing a catalyst at 150℃ under mild conditions. This research paves the way for future high-performance polymers that are completely recyclable.

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