Polymerization of isoprene initiated by α, ω-dilithiopolyisoprene: 7Li NMR study of lonic species
✍ Scribed by Abdelaziz El Madani; Joël Belleney; Jean-Claude Favier; Patrick Hémery; Pierre Sigwalt
- Book ID
- 104528614
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 445 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0959-8103
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✦ Synopsis
Abstract
^7^Li nuclear magnetic resonance (NMR) of dilute solutions in hexane of α, ω‐dilithiopolyisoprenes with two degrees of polymerization (DP) values was studied at several temperatures. For DP ≈ 500, the spectrum is similar to that of monofunctional poly(isoprenyl)lithium. When the DP is low (e.g. 80) new resonances appear upfield, showing the existence of more aggregated species. Their formation was attributed to the ability of dilithio compounds to undergo cyclization by intramolecular association. These observations and a computer simulation permit us to explain the kinetics of polymerization.