Radical polymerization of phenyl acrylate as studied by ESR spectroscopy: Concurrence of propagating and mid-chain radicals

Azukizawa, Makoto, Yamada, Bunichiro, Hill, David J. T. and Pomery, Peter J. (2000) Radical polymerization of phenyl acrylate as studied by ESR spectroscopy: Concurrence of propagating and mid-chain radicals. Macromolecular Chemistry and Physics, 201 7: 774-781. doi:10.1002/(SICI)1521-3935(20000401)201:7<774::AID-MACP774>3.0.CO;2-K


Author Azukizawa, Makoto
Yamada, Bunichiro
Hill, David J. T.
Pomery, Peter J.
Title Radical polymerization of phenyl acrylate as studied by ESR spectroscopy: Concurrence of propagating and mid-chain radicals
Journal name Macromolecular Chemistry and Physics   Check publisher's open access policy
ISSN 1022-1352
1521-3935
Publication date 2000-04
Sub-type Article (original research)
DOI 10.1002/(SICI)1521-3935(20000401)201:7<774::AID-MACP774>3.0.CO;2-K
Volume 201
Issue 7
Start page 774
End page 781
Total pages 8
Place of publication Zug, Switzerland
Publisher Wiley-VCH Verlag
Collection year 2000
Language eng
Subject C1
250504 Polymerisation Mechanisms
780103 Chemical sciences
Formatted abstract
The electron spin resonance (ESR) spectrum of the propagating radical of phenyl acrylate (PhA) was successfully recorded in benzene as a non-polar solvent. The hyperfine coupling constants for the α and β-protons were evaluated on the basis of the spectra of the propagating radicals of PhA and phenyl acrylate-α-d. The simulated spectrum satisfactorily fits those observed during polymerization, and the spectrum of the poly(PhA) radical obtained at low conversion (<15%) was assigned to the propagating radical. The spectra observed at higher conversions (>15%) indicated the presence of two types of radical species, a propagating radical and a mid-chain radical produced by abstraction of the α-hydrogen of the monomeric unit. The content of branching in the polymers as a result of the formation of a mid-chain radical was found to be 1–3% by 13C NMR spectroscopy. The absolute rate constants for propagation (kp) and termination (kt) of PhA at low conversions were determined based on the quantification of the propagating radical by ESR spectroscopy at 60°C: kp = 3 580 dm3·mol–1·s–1 and kt = 6,8×106 dm3·mol–1·s–1. However, these seemed to be apparent values because the propagating radical is expected to be converted to the mid-chain radical by intra- and intermolecular hydrogen abstraction before the loss of its activity by bimolecular termination. Conversion from the propagating radical to the mid-chain radical followed by reinitiation was estimated to occur more than twenty times during the lifetime of each polymer chain.
© WILEY-VCH Verlag GmbH
Keyword Polymer science
Electron-spin-resonance
Pulsed-laser polymerization
Evaluated rate coefficients
Methyl-methacrylate
Butyl acrylate
Nmr-spectroscopy
Rate constants
Homogeneous polymerization
Emulsion polymerization
Vinyl-acetate
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemistry and Molecular Biosciences
 
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Created: Tue, 10 Jun 2008, 12:02:17 EST