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A base-conjugate-acid pair for living/controlled ring-opening polymerization of trimethylene carbonate through hydrogen-bonding bifunctional synergistic catalysis

The ring-opening polymerization (ROP) of trimethylene carbonate (TMC) using a base-acid binary organocatalyst system of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) and Brønsted acid trifluoromethanesulfonic acid (TFA) with benzyl alcohol (BnOH) as the initiator has been investigated. The MTB...

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Bibliographic Details
Published in:Polymer chemistry 2014-10, Vol.5 (2), p.651-659
Main Authors: Wang, Xin, Cui, Saide, Li, Zhenjiang, Kan, Suli, Zhang, Qiguo, Zhao, Chengxu, Wu, Hao, Liu, Jingjing, Wu, Wenzhuo, Guo, Kai
Format: Article
Language:English
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Summary:The ring-opening polymerization (ROP) of trimethylene carbonate (TMC) using a base-acid binary organocatalyst system of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) and Brønsted acid trifluoromethanesulfonic acid (TFA) with benzyl alcohol (BnOH) as the initiator has been investigated. The MTBD and its conjugate-acid pair H-bonding bifunctional synergistic activation mechanism was demonstrated by NMR measurements, and the living/controlled nature of MTBD/TFA catalyzed ROP of TMC was confirmed by the kinetic and chain extension experiments. The controlled ROP of TMC with the optimal molar ratio of MTBD/TFA = 2/1 proceeded to afford well-defined PTMC with narrow molecular weight distributions ( M w / M n ∼ 1.1). The molecular weights determined by 1 H NMR are in precise agreement with the theoretical values. 1 H NMR, SEC, and MALDI-ToF MS measurements confirmed the structure of the obtained homopolymer PTMC. In addition, a diblock copolymer consisting of poly(trimethylene carbonate) and poly( l -lactide) (PTMC- b -PLLA) was synthesized successfully by the MTBD/TFA binary catalyst system. Base-conjugate-acid pair in H-bond donor/acceptor organocatalysis in living polymerization was firstly reported as a general workable protocol in the ROPs.
ISSN:1759-9954
1759-9962
DOI:10.1039/c4py00773e