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A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes
Published on: February 27, 2017
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Borane-catalysed cyclodepolymerization of CO2-derived polycarbonates
Mikhailey D Wheeler1, Francesca M Kerton1
1Department of Chemistry, Memorial University, St. John's, NL, A1B 3X7, Canada. fkerton@mun.ca.
Faraday Discussions
|September 16, 2025
Summary
Tris(pentafluorophenyl)borane (BCF) selectively depolymerizes polycarbonates into cyclic carbonates. This Lewis acid catalyst is effective at low loadings and moderate temperatures, operating via a chain-end backbiting mechanism.
Area of Science:
- Polymer Chemistry
- Catalysis
- Organic Synthesis
Background:
- Polycarbonate recycling remains a challenge.
- Developing efficient depolymerization catalysts is crucial for sustainable polymer management.
Purpose of the Study:
- To investigate the catalytic activity of tris(pentafluorophenyl)borane (BCF) for polycarbonate depolymerization.
- To determine the optimal conditions and mechanism for BCF-catalyzed polycarbonate degradation.
Main Methods:
- Catalytic depolymerization of poly(propylene carbonate) (PPC) and poly(cyclohexene carbonate) (PCHC) using BCF in toluene.
- Kinetic studies using in situ infrared spectroscopy.
- Reaction mechanism elucidation via 1H NMR spectroscopy and gel permeation chromatography.
Main Results:
- BCF selectively depolymerizes PPC and PCHC to cyclic carbonates with high conversion at 2.5 mol% catalyst loading and 75 °C.
- Kinetic analysis revealed distinct activation energies and entropies for PPC and PCHC depolymerization.
- The reaction proceeds via a chain-end backbiting mechanism, not random chain scission.
- Water was found to inhibit the depolymerization reaction.
Conclusions:
- Tris(pentafluorophenyl)borane is an effective co-catalyst-free Lewis acid catalyst for polycarbonate depolymerization.
- The reaction efficiency is dependent on the polycarbonate structure and the presence of impurities like water.
- Understanding the mechanism provides insights for designing future depolymerization strategies.
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