High-temperature polymerization of styrene: Mechanism determination with preparative gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and 13C nuclear magnetic resonance
✍ Scribed by J. D. Campbell; J. A. Allaway; F. Teymour; M. Morbidelli
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 317 KB
- Volume
- 94
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Abstract
An experimental study designed to elucidate mechanistic details regarding the thermal polymerization of styrene between 260 and 340°C is reported. The data show that back‐biting to the third or fifth carbon from the chain end, followed by β scission, is the dominant chain‐producing reaction in the molecular weight development. This conclusion is supported by the ^13^C‐NMR data coupled with preparative gel permeation chromatography, which show that the predominant low‐molecular‐weight oligomers are 2,4‐diphenyl‐1‐butene and 2,4,6‐triphenyl‐1‐hexene, that is, the products of the 1:3 and 1:5 back‐biting/β‐scission reactions, respectively. The presence of head‐to‐head or head‐to‐tail branching, due to chain transfer to the polymer or back‐biting, is shown to be negligible through ^13^C‐NMR analysis. Finally, the distribution of terminal unsaturations, determined by the relative rates of termination, back‐biting, and chain transfer to polymer, has been measured with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. This has shown that the back‐biting/β‐scission reaction dominates the molecular weight development in comparison with either termination or chain transfer to the polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 890–908, 2004