Anionic polymerization of isoprene, butadiene and styrene with 3-dimethylaminopropyllithium

Stergios Pispas, Marinos Pitsikalis, Nikolaos Hadjichristidis*, Patrizia Dardani, Francesco Morandi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The synthesis of dimethylaminopropyllithium (DMAPLi), from the corresponding chloride and lithium metal, by using high-vacuum techniques, is described. DMAPLi was purified by crystallization under vacuum. Gas chromatography-mass spectrometry analysis of the purified product, after neutralization with degassed methanol, showed the existence of ∼ 2% impurities. The most important of these impurities (∼ 1.5%) were tetramethylhexamethylenediamine and dimethylaminohex-1-ene. By using DMAPLi as initiator, several polymerizations of isoprene, butadiene and styrene were carried out in benzene, under high-vacuum conditions. The molecular-weight range of the polymers obtained was from about 3 × 103 to 4 × 104. The polydispersity index (I = Mw/Mn) of the polydienes was similar (I < 1.1) to those obtained with the classical initiator s-butyllithium, but the vinyl content was higher. It was found that the lower the molecular weight of the polydienes, the higher the vinyl content. In the case of styrene, the polydispersity index of the polystyrenes produced was relatively high (I = 1.2 to 1.5), but by adding small amounts of tetrahydrofuran or by using unpurified initiator, which contains polar impurities, the polydispersity index recovers the usual values, for molecular weights higher than ∼ 1 × 104.

Original languageEnglish (US)
Pages (from-to)3005-3011
Number of pages7
JournalPolymer
Volume36
Issue number15
DOIs
StatePublished - Jan 1 1995

Keywords

  • 3-dimethylaminopropyllithium
  • anionic polymerization
  • polydispersity

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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