Relation between the reactivities of vinyl monomers in ionic polymerizations and their 1H NMR spectra |
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Authors: | Koichi Hatada Tatsuki Kitayama Takafumi Nishiura Wataru Shibuya |
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Institution: | 1. Department of Applied Physics and Chemistry, Fukui University of Technology, 3-6-1 Gakuen, Fukui-shi 910-8505, Japan;2. Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan |
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Abstract: | 1H NMR chemical shifts of the protons in the vinyl groups of monomers are correlated with their reactivities in anionic, coordinated anionic, and cationic polymerizations. The relative reactivities of styrenes in anionic addition reactions with living polystyrene increase linearly with the chemical shift of the proton trans to the substituent (δH1). Only the plot for 2,4,6-trimethylstyrene deviates very much from the linear relation because of the large steric hindrance. The relative reactivities of methacrylates in anionic copolymerizations increase with increasing chemical shifts of protons attached to the β-carbon of methacrylates. In cationic polymerizations of styrenes, the relative reactivities decrease with increasing δH1. The relative reactivities in coordinated anionic polymerizations with Ti-containing Ziegler initiators show a typical feature of cationic polymerization, and those with V-containing initiators show a typical feature of anionic polymerization, indicating the importance of the coordination process in the propagation reaction with Ti-containing initiator systems. From the results, it can be concluded that the chemical shifts of the protons attached to the β-carbon of vinyl monomers can be used as a practical measure of the reactivity of vinyl monomers in ionic polymerizations and also as a tool for understanding the mechanism of polymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2134–2147, 2002 |
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Keywords: | 1H NMR anionic polymerization cationic polymerization coordinated anionic polymerization styrenes methacrylates vinyl ethers 13C NMR |
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