Hindered lithium dialkylamide initiators for the living anionic polymerization of methacrylic esters

Timothy Edward Long, R. A. Guistina, B. A. Schell, J. E. Mcgrath

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Lithium diisopropylamide is an efficient initiator for the anionic polymerization of methyl methacrylate in polar solvents at –78°C. Predictable molecular weights based on the initiator concentration were obtained, yields were quantitative, and molecular weight distributions were relatively narrow (<1.30). The presence of an amino end group and confirmation of the initiation mechanism were confirmed by potentiometric titration using HClO4. Number‐average molecular weights determined by titration agreed well with values determined by SEC. Other lithium dialkylamides that contain larger alkyl groups such as lithium diisobutylamide were less efficient initiators. This was attributed to the more nucleophilic anion due to less steric hindrance near the nitrogen atom. Molecular weight distributions were significantly broadened (>2.0), and molecular weight control was not achieved. However, polymer yields were quantitative. In all cases, PMMA stereochemistry was indicative of a solvent‐separated lithium counterion, and triad compositions were identical to organolithium initiated homopolymers, i.e., 78% syndiotactic, 20% heterotactic, and 2% isotactic. © 1994 John Wiley & Sons, Inc.

Original languageEnglish
Pages (from-to)2425-2430
Number of pages6
JournalJournal of Polymer Science Part A: Polymer Chemistry
Volume32
Issue number13
DOIs
Publication statusPublished - 1994 Jan 1
Externally publishedYes

Fingerprint

Living polymerization
Anionic polymerization
Lithium
Esters
Molecular weight
Weight control
Stereochemistry
Methacrylates
Polymethyl Methacrylate
Molecular weight distribution
Homopolymerization
Polymers
Chemical analysis
diisopropylamine

Keywords

  • anionic
  • living
  • methyl methacrylate
  • polymerization

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

Cite this

Hindered lithium dialkylamide initiators for the living anionic polymerization of methacrylic esters. / Long, Timothy Edward; Guistina, R. A.; Schell, B. A.; Mcgrath, J. E.

In: Journal of Polymer Science Part A: Polymer Chemistry, Vol. 32, No. 13, 01.01.1994, p. 2425-2430.

Research output: Contribution to journalArticle

Long, Timothy Edward ; Guistina, R. A. ; Schell, B. A. ; Mcgrath, J. E. / Hindered lithium dialkylamide initiators for the living anionic polymerization of methacrylic esters. In: Journal of Polymer Science Part A: Polymer Chemistry. 1994 ; Vol. 32, No. 13. pp. 2425-2430.
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