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Neodymium(III) tert ‐Butoxide‐Dialkylmagnesium, a New Initiator System for Syndiotactic Polymerization of Methyl Methacrylate
Author(s) -
Gromada Jérôme,
Fouga Christine,
Chenal Thomas,
Mortreux André,
Carpentier JeanFrançois
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20020201)203:3<550::aid-macp550>3.0.co;2-h
Subject(s) - polymer chemistry , tacticity , methyl methacrylate , polymerization , dispersity , chemistry , polymer , reactivity (psychology) , anionic addition polymerization , materials science , organic chemistry , medicine , alternative medicine , pathology
The polymerization of methyl methacrylate (MMA) in toluene at 0°C using combinations of dihexylmagnesium (Hex 2 Mg) with various metal tert ‐butoxides as initiators has been studied. Purely anionic initiator systems based on alkali metal salts allow complete conversion of MMA within 1 h to yield either highly isotactic PMMA (LiO t ‐Bu/MgR 2 = 5, M̄ n = 61 000, M̄ w / M̄ n = 1.95, 84% mm ) or narrow polydispersity atactic PMMA (NaO t ‐Bu/MgR 2 = 20, M̄ n = 39 000 and M̄ w / M̄ n = 1.18). The combination of Hex 2 Mg with Nd 3 (O t ‐Bu) 9 (THF) 2 (Nd/Mg = 5–10) affords a novel initiator system that gives in 40–63% yield syndiotactic‐rich PMMA ( M̄ n = 50–90 000, M̄ w / M̄ n = 1.06–1.12, 76–79% rr ) with low initiation efficiency. In this case, characteristics of the polymers and polymerization reactivity data are consistent with the in situ generation of an alkylneodymium species.