Theoretical Mechanistic Investigation into Metal-Free Alternating Copolymerization of CO2 and Epoxides: The Key Role of Triethylborane

Dan Dan Zhang, Xiaoshuang Feng*, Yves Gnanou, Kuo Wei Huang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The copolymerization of carbon dioxide (CO2) and epoxides has received much attention during the past decades for the production of aliphatic polycarbonates. Remarkably, the green synthesis of polycarbonates was recently demonstrated by copolymerization of CO2 with epoxides under metal-free conditions. In this work, the reaction mechanism of this highly selective polymerization was further investigated using DFT calculations. Four steps were studied: step I describes the epoxide ring-opening by the chloride anion in the presence of the Lewis acid triethylborane (TEB); step II is related to the subsequent insertion of CO2; step III corresponds to the alternating insertion of an epoxide facilitated by TEB; step IV is characterized by the leaving of TEB followed by a new round of polymerization. The high selectivity to form alternating polycarbonates and the suppression of backbiting and homopolymerization that respectively generate cyclic carbonates and polyethers were confirmed by the difference of energy barriers. The key role of TEB at every step was also elucidated. Our theoretical results support the proposed experimental outcomes and provide the fundamental mechanistic insights.

Original languageEnglish (US)
Pages (from-to)5600-5607
Number of pages8
JournalMacromolecules
Volume51
Issue number15
DOIs
StatePublished - Aug 14 2018

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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