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Study of the propagation centre in the anionic polymerization of acrylic monomers, 1. Spectroscopic study of methyl 2-lithioisobutyrate, an initiator for the anionic polymerization of acrylic monomers

✍ Scribed by Jaroslav Kříž; Jiří Dybal; Petr Vlček; Miroslav Janata


Publisher
John Wiley and Sons
Year
1994
Tongue
English
Weight
824 KB
Volume
195
Category
Article
ISSN
1022-1352

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✦ Synopsis


Abstract

As the simplest model for the propagation centre in the anionic polymerization of methyl methacrylate, the solution of methyl 2‐lithioisobutyrate (1) in tetrahydrofuran was studied by means of ^1^H, ^6^Li, ^7^Li and ^13^C nuclear magnetic resonance (NMR), and Raman spectroscopy at various concentrations and temperatures. A system of equilibria of differently solvated dimeric, tetrameric and two isomeric trimeric aggregates was found and their thermodynamic constants were established. On the basis of the analysis of NMR chemical shifts, heteronuclear nuclear Overhauser effect correlation spectroscopy (NOESY) spectra and relaxation data, structures of the aggregates are suggested. The kinetics of the exchange between the aggregates and the lifetime of individual aggregates was established. The results suggest that the aggregation can interfere with initiation in the early steps of anionic polymerization of acrylics.


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