Jean Raynaud
University of Bordeaux
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Publication
Featured researches published by Jean Raynaud.
Journal of the American Chemical Society | 2009
Jean Raynaud; Christelle Absalon; Yves Gnanou; Daniel Taton
An N-heterocyclic carbene (NHC), namely, 1,3-bis-(diisopropyl)imidazol-2-ylidene (1), was demonstrated to bring about the metal-free ring-opening polymerization of ethylene oxide at 50 degrees C in dimethyl sulfoxide, in absence of any other reagents. Poly(ethylene oxide) (PEO) of polydispersities <1.2 and molar masses perfectly matching the [monomer]/[(1)] ratio could thus be obtained in quantitative yields, attesting to the controlled/living character of such carbene-initiated polymerizations. It is argued that (1) adds to ethylene oxide to form a zwitterionic species, namely 1,3-bis-(diisopropyl)imidazol-2-ylidinium alkoxide, that further propagates by a zwitterionic ring-opening polymerization (ZROP) mechanism. Through an appropriate choice of terminating agent NuH or NuSiMe(3) at the completion of the polymerization, a variety of end-functionalized PEO chains could be generated. In particular, alpha,omega-bis(hydroxy)-telechelic PEO, alpha-benzyl,omega-hydroxy, and alpha-azido,omega-hydroxy-difunctionalized PEOs were synthesized by NHC (1)-initiated ZROP, using H(2)O, PhCH(2)OH, and N(3)SiMe(3) as terminating agent, respectively. Characterization of these alpha,omega-difunctionalized PEOs by techniques such as (1)H NMR spectroscopy, MALDI-TOF spectrometry, and size exclusion chromatography confirmed the quantitative introduction of functional groups at both alpha and omega positions of the PEO chains and the formation of very narrow molar mass polymers. Finally, the synthesis of a poly(ethylene oxide)-b-poly(epsilon-caprolactone) diblock copolymer by sequential ZROP of the corresponding monomers was successfully achieved using (1) as organic initiator without isolation of the PEO block intermediate.
Chemical Communications | 2010
Jean Raynaud; Winnie Nzahou Ottou; Yves Gnanou; Daniel Taton
A N-heterocyclic carbene, namely, 1,3-bis-(diisopropyl)imidazol-2-ylidene either directly initiates or catalyzes the metal-free ring opening polymerization of neat propylene oxide at 50 degrees C, affording well-defined alpha,omega-heterodifunctionalized poly(propylene oxide) oligomers.
Polymer Chemistry | 2011
Jean Raynaud; Na Liu; Maréva Fèvre; Yves Gnanou; Daniel Taton
Unsaturated N-heterocyclic carbenes (NHCs) such as 1,3-bis(di-isopropyl)imidazol-2-ylidene (1) and 1,3-bis(di-tert-butyl)imidazol-2-ylidene (2) are shown to catalyze the sequential group transfer polymerization (GTP) of (meth)acrylic monomers. A variety of block copolymers including not only alkyl methacrylate but also alkyl acrylate monomer units as well as blocks deriving from N,N-dimethylacrylamide and methacrylonitrile were thus obtained at room temperature, using 1-methoxy-2-methyl-1-trimethylsiloxypropene (MTS) as initiator in THF as solvent. Block copolymerizations could be achieved, starting indifferently from the GTP of the acrylic monomer to that of the methacrylic one or vice versa, that is, regardless of the order of addition of the two monomers, in contrast to most examples of block copolymer synthesis by “controlled/living” sequential polymerization. It is postulated that these NHC-catalyzed GTPs of (meth)acrylics proceed via a single step concerted-like associative mechanism, involving the formation of thermodynamically unstable intermediates or transition states, likely hypervalent siliconates, with no detectable anionic enolates formed.
Angewandte Chemie | 2008
Jean Raynaud; Andrés E. Ciolino; Antoine Baceiredo; Mathias Destarac; Fabien Bonnette; Tsuyoshi Kato; Yves Gnanou; Daniel Taton
Macromolecules | 2009
Jean Raynaud; Yves Gnanou; Daniel Taton
Macromolecules | 2010
Jean Raynaud; Christelle Absalon; Yves Gnanou; Daniel Taton
Macromolecules | 2010
Jean Raynaud; Na Liu; Yves Gnanou; Daniel Taton
Archive | 2008
Mathias Destarac; Gerard Mignani; Antoine Baceiredo; Daniel Taton; Yves Gnanou; Jean Raynaud
Archive | 2009
Jean Raynaud; Yves Gnanou; Daniel Taton
Archive | 2009
Jean Raynaud; Yves Gnanou; Daniel Taton