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<p>Various combinations of commercially available Lewis bases (1-methylimidazole, 4-(dimethylamino)pyridine, 1,4-diazabicyclo[2.2.2]octan and 1,8-diazabicyclo[5.4.0]undec-7-ene) were employed alongside phenyl glycidyl ether as a co-catalyst for the polymerization and depolymerization of polyester compounds. During the glycolysis-based degradation of commercial-grade PET, it was found that only 1-methylimidazole enhances the reaction kinetics when combined with oxirane, resulting in a drastic reduction in degradation time. This phenomenon can be explained by the in situ formation of an N-heterocyclic carbene through the reaction between the azole and the oxirane. In the polymerization of <i>ε</i>-caprolactone, 1,8-diazabicyclo[5.4.0]undec-7-ene is the only Lewis base that yields moderate conversion (64%) under the applied conditions (90&#xa0;°C, 24&#xa0;h reaction time, no solvent). Adding benzyl alcohol as an initiator resulted in faster, higher conversion for diazabicyclo[5.4.0]undec-7-ene but had no effect on the other Lewis bases. When the oxirane was added as the sole co-catalyst, all Lewis bases fully polymerized the lactone within 24&#xa0;h. The fastest polymerization was achieved by adding benzyl alcohol to the Lewis base/oxirane catalytic system, as complete polymerization of the lactone occurred within 1&#xa0;h.</p> Graphical abstract <p></p>

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Lewis base/oxirane combinations as catalytic system in the glycolysis of poly(ethylene terephthalate) and the ring-opening polymerization of ε-caprolactone

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  • 发表日期：

    2026年4月21日

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  • Matthias R. Steiner,
  • Cordula M. Zeiler,
  • Christian Slugovc

摘要

Various combinations of commercially available Lewis bases (1-methylimidazole, 4-(dimethylamino)pyridine, 1,4-diazabicyclo[2.2.2]octan and 1,8-diazabicyclo[5.4.0]undec-7-ene) were employed alongside phenyl glycidyl ether as a co-catalyst for the polymerization and depolymerization of polyester compounds. During the glycolysis-based degradation of commercial-grade PET, it was found that only 1-methylimidazole enhances the reaction kinetics when combined with oxirane, resulting in a drastic reduction in degradation time. This phenomenon can be explained by the in situ formation of an N-heterocyclic carbene through the reaction between the azole and the oxirane. In the polymerization of ε-caprolactone, 1,8-diazabicyclo[5.4.0]undec-7-ene is the only Lewis base that yields moderate conversion (64%) under the applied conditions (90 °C, 24 h reaction time, no solvent). Adding benzyl alcohol as an initiator resulted in faster, higher conversion for diazabicyclo[5.4.0]undec-7-ene but had no effect on the other Lewis bases. When the oxirane was added as the sole co-catalyst, all Lewis bases fully polymerized the lactone within 24 h. The fastest polymerization was achieved by adding benzyl alcohol to the Lewis base/oxirane catalytic system, as complete polymerization of the lactone occurred within 1 h.

Graphical abstract