Electronic and steric ligand effects in the radical polymerization of vinyl acetate mediated by β-ketoiminate complexes of cobalt(II)

K. S. Santhosh Kumar, Yugang Li, Yves Gnanou*, Ulrich Baisch, Yohan Champouret, Rinaldo Poli, Kiyoshi C.D. Robson, W. Stephen McNeil

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Complexes Co[OC(Ph)CHC(Me)NAr]2 [Ar=Ph, 1; o,o′-C 6H3Me2 (Xyl), 2; p-C6H 4CF3, 3] are tested in the polymerization of vinyl acetate (VAc) initiated by V-70 (0.8 equiv) at 30°C. Polymerization occurs without any notable induction time yielding PVAc with relatively low polydispersity, but with higher than expected Mn values, which indicates inefficient trapping processes. The appar- ent polymerization rate constant varies in the order 2>1>3. Controlled polymer growth is also observed when the polymerization is conducted in the presence of a much higher V-70/1 ratio, demonstrating that this system can also function as a transfer agent in a degenerative transfer process. Competition between chain growth and catalyzed chain transfer (CCT) is also observed, the latter prevailing at higher temperatures. Comparison of these results with previous reports on bis(β-diketonato) complexes allows a separate assessment of ligand electronic and steric effects in the ability to control polymerization.

Original languageEnglish (US)
Pages (from-to)1257-1265
Number of pages9
JournalChemistry - An Asian Journal
Volume4
Issue number8
DOIs
StatePublished - Aug 3 2009

Keywords

  • Cobalt
  • Lewis bases
  • Ligand effects
  • Polymerization
  • Radicals

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry
  • Organic Chemistry

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