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Ring‐Opening Polymerization of ε ‐Caprolactone by Phosphorane Iminato and Cyclopentadienyl Complexes of Rare Earth Elements
Author(s) -
Ravi Palaniswamy,
Gröb Thorsten,
Dehnicke Kurt,
Greiner Andreas
Publication year - 2001
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(20010801)202:12<2641::aid-macp2641>3.0.co;2-q
Subject(s) - caprolactone , cyclopentadienyl complex , polymer chemistry , chemistry , ring opening polymerization , polymerization , dispersity , copolymer , organic chemistry , catalysis , polymer
Rare earth element complexes with triphenyl phosphorane iminato ligands such as [La 2 (NPPh 3 ) 4 (μ‐NPPh 3 ) 2 (μ‐THF)] and [Yb(NPPh 3 ) 3 ] 2 initiate the polymerization of ε ‐caprolactone to give high molecular weight poly( ε ‐caprolactone) with moderate polydispersity. The reactivity of these complexes is higher as compared to complexes with three cyclopentadienyl ligands with corresponding metal centers. The initiation mechanism for the polymerization of ε ‐caprolactone by [La 2 (NPPh 3 ) 4 (μ‐NPPh 3 ) 2 (μ‐THF)] is discussed based on the end groups of low molecular weight polycaprolactones. Living chain ends of poly( ε ‐caprolactone) were proved by block copolymerization of ε ‐caprolactone and δ ‐valerolactone. The mixed complex [Cp 3 Dy 2 (NPPh 3 ) 3 ] has been successfully applied for ROP of CL. A significant increase in molecular weight of ROP has been observed with decrease of reaction temperature.