Phosphazene-Promoted Metal-Free Ring-Opening Polymerization of Ethylene Oxide Initiated by Carboxylic Acid

The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation of carboxylic acid to hydroxyl ester, followed by...

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Bibliographic Details
Published in:Macromolecules 2014-03, Vol.47 (5), p.1693-1698
Main Authors: Zhao, Junpeng, Pahovnik, David, Gnanou, Yves, Hadjichristidis, Nikos
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Physicochemistry of polymers
Polymerization
Polymers and radiations
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Summary:The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation of carboxylic acid to hydroxyl ester, followed by slow chain growth together with simultaneous and fast end-group transesterification, which led to poly(ethylene oxide) (PEO) consisting of monoester (monohydroxyl), diester, and dihydroxyl species. An appropriate t-BuP4/acid ratio was proven to be essential to achieve better control over the polymerization and low dispersity of PEO. This work provides important information and enriches the toolbox for macromolecular and biomolecular engineering with protic initiating sites.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma500067j