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Ring‐opening polymerization of ε‐caprolactone initiated by rare earth alkoxides and borohydrides: a comparative study
Author(s) -
Palard Isabelle,
Schappacher Michèle,
Soum Alain,
Guillaume Sophie M
Publication year - 2006
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1984
Subject(s) - caprolactone , polymerization , alkoxide , borohydride , chemistry , polymer chemistry , molar mass , ring opening polymerization , monomer , polymer , organic chemistry , catalysis
The polymerization of ε‐caprolactone initiated by trivalent rare earth (Ln) derivatives, namely the isopropoxide ‘Ln(OiPr) 3 ’ opposed to the borohydride Ln(BH 4 ) 3 (THF) 3 (Ln = La, Nd, Sm) and (Cp*) 2 Sm(BH 4 )(THF) (Cp* = (η‐C 5 Me 5 )), has been evaluated. The comparison, based on the structure of the initiator and on the polymerization features (molar mass, molar mass distribution, side reactions) reveals some differences especially in the number of active polymer chains per metal and in the occurrence of some transfer reactions with Ln(BH 4 ) 3 (THF) 3 . Polymerizations performed with borohydride derivatives lead to a gel as a result of van der Waals interactions, while the reaction medium remains fluid with the alkoxide species. A typical coordination‐insertion mechanism with oxygen‐acyl bond cleavage of the monomer prevails with both types of initiators. However, while the alkoxide complexes lead to α,ω‐hydroxyalkoxypoly(ε‐caprolactone), the borohydride compounds allow the synthesis of α,ω‐dihydroxypoly(ε‐caprolactone). Both polymerization processes are well controlled under specific conditions. Copyright © 2006 Society of Chemical Industry