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Anionic coordinated polymerization of ε ‐caprolactone with aluminium, zirconium and some rare earths alkoxides as initiators in the presence of alcohols
Author(s) -
MiolaDelaite Christelle,
Hamaide Thierry,
Spitz Roger
Publication year - 1999
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/(sici)1521-3935(19990701)200:7<1771::aid-macp1771>3.0.co;2-v
Subject(s) - polymerization , chemistry , polymer chemistry , zirconium , monomer , alkoxide , caprolactone , transesterification , benzyl alcohol , chain transfer , alcohol , ring opening polymerization , lewis acids and bases , polymer , organic chemistry , catalysis , radical polymerization
The kinetics of the polymerization of ε ‐caprolactone initiated with various Lewis acid metal alkoxides (Al, Zr and rare earths such as Y, Sm, Nd) in the presence of excess alcohol has been investigated. Whatever the metal, the activity depends strongly on the [Alcohol]/[Metal] ratio and goes through a maximum, except for Zr, for which the increase of alcohol concentration leads to a continuous decrease of the reaction rate. The activities obtained for zirconium butoxide as initiator are lower than for aluminium isopropoxide at room temperature but the activation energy is higher. No transesterification reactions have been noticed during polymerization. The polymerization can be described according to a living process with fast transfer reaction, so that the molecular weight is easily controlled by the [Monomer]/[Alcohol] ratio. Rare earths alkoxides (Y, Sm, Nd) result in higher activities. Although some transesterification reactions are observed if leaving the polymer chains in contact with the active centers, functionalized oligomers can be obtained within less than 5 min with yttrium or samarium isopropoxide as initiators and benzyl alcohol in excess.