Yves Gnanou

King Abdullah University of Science and Technology, Djidda, Makkah, Saudi Arabia

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Publications (177)761.65 Total impact

  • Wei Zhao · Yves Gnanou · Nikos Hadjichristidis
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    ABSTRACT: A new method, based on hydrogen-bonding organocatalysis, was developed to achieve living ring-opening polymerization of N-carboxyanhydride of α-amino acids using aminoalcohols as initiators in the presence of N, N’-bis[3,5-bis(trifluoromethyl)phenyl]thiourea (TU-S). The thiourea provides, through hydrogen bonding, simultaneous activation of NCA monomers/reversible deactivation of polymer chain-ends/silencing of the tertiary amine and thus allows the polymerization to proceed in a high controllable mode. For example, using N,N-dimethyl ethanolamine (DMEA), as initiator in the presence of TU-S, a series of well-defined linear polypeptides with different designed MWs (3.01×104 – 18.10×104) and low PDI values (1.02 - 1.05) were successfully synthesized. This general strategy was also extended to the synthesis of well-defined di- and multi-armed polypeptides by using di-, tri-, or tetra-aminoalcohol initiators (methyldiethanolamine (MDEA), triethanolamine (TEA) or N,N,N’,N’-tetrakis(2-hydroxyethyl)ethylenediamine (THEED)) in the presence of TU-S.
    07/2015; DOI:10.1039/C5PY00874C
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    ABSTRACT: Novel well-defined polyethylene-based random, block, and bilayered molecular cobrushes were synthesized through the macromonomer strategy. Two steps were involved in this approach: (i) synthesis of norbornyl-terminated macromonomers of polyethylene (PE), polycaprolactone (PCL), poly(ethylene oxide) (PEO), and polystyrene (PS), as well as polyethylene-b-polycaprolactone (PE-b-PCL), by esterification of the hydroxyl-terminated precursors (PE, PCL, PEO, PS, and PE-b-PCL) with 5-norbornene-2-carboxylic acid and (ii) ring-opening metathesis (co)polymerization of the resulting macromonomers to afford the PE-based molecular cobrushes. The PE-macromonomers were synthesized by polyhomologation of dimethylsulfoxonium methylide, while the others by anionic polymerization. Proton nuclear magnetic resonance spectroscopy (1H NMR) and high-temperature gel permeation chromatography (HT-GPC) were used to imprint the molecular characteristics of all macromonomers and molecular brushes and differential scanning calorimetry (DSC) for the thermal properties. The bilayered molecular cobrushes of P(PE-b-PCL) adopt a wormlike morphology on silica wafer as visualized by atomic force microscopy (AFM).
    Macromolecules 05/2015; 48(11):150528151436004. DOI:10.1021/acs.macromol.5b00713 · 5.93 Impact Factor
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    ABSTRACT: A novel strategy, based on the in situ generated boron-thexyl-silaboracyclic initiating sites for the polyhomologation of dimethylsulfoxonium methylide, has been developed for the synthesis of complex polyethylene-based architectures. As examples, the synthesis of a 4-arm polyethylene star, three (polystyrene)(polyethylene)2 3-miktoarm stars and a PE-branched double graft copolymer is given.
    Chemical Communications 04/2015; 51(49). DOI:10.1039/c5cc01579k · 6.83 Impact Factor
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    Wei Zhao · Yves Gnanou · Nikos Hadjichristidis
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    ABSTRACT: A novel highly efficient strategy, based on an "alliance" of primary and secondary amine initiators, was successfully developed allowing the fast and living ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCAs) at room temperature.
    Biomacromolecules 03/2015; 16(4). DOI:10.1021/acs.biomac.5b00134 · 5.75 Impact Factor
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    Wei Zhao · Yves Gnanou · Nikos Hadjichristidis
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    ABSTRACT: By associating primary (slow but controlled ring-opening polymerization; ROP) and tertiary (fast but uncontrolled ROP) amines in the same molecule, a novel highly active organocatalytic system proceeding by an accelerated amine mechanism through monomer activation (AAMMA) and leading to living ROP of α-amino acid N-carboxyanhydrides at room temperature was successfully developed.
    Chemical Communications 02/2015; 51(17). DOI:10.1039/c4cc09055a · 6.83 Impact Factor
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    ABSTRACT: A series of novel, well-defined triblock (PnBVE-b-PCEVE-b-PSiDEGVE) and pentablock (PSiDEGVE-b-PCEVE-b-PnBVE-b-PCEVE-b-PSiDEGVE) terpolymers of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiEGVE) were synthesized by sequential base-assisted living cationic polymerization. The living character of the homopolymerization of the three VE monomers and the crossover reaction resulting in the formation of well-defined block copolymers were investigated in various solvents (toluene, dichloromethane and n-hexane) using either a monofunctional [nBVE-acetic acid adduct (nBEA), CEVE-acetic acid adduct (CEEA) and SiDEGVE-acetic acid adduct (SiDEGEA)] or a difunctional [1,4-cyclohexane-1,4-diyl bis(2-methoxyethyl acetate) (cHDMEA)] initiator. All initiators are structurally equivalent to the dormant species of the corresponding monomers in order to achieve fast initiation. The optimal conditions of polymerizations were achieved in n-hexane at -20°C, in the presence of 1 M AcOEt (base). Good control over the number average molecular weight (Mn) and the polydispersity index (PDI) was obtained only at [Et3Al2Cl3]0 = [Chain-end]0 ≤ 10 mM. 2,6-di-tert-butylpyridine (DtBP) was used as a non-nucleophilic proton trap to neutralize any protonic initiation from moisture (i.e., Et3Al2Cl3.H2O). Well-defined PnBVEn-b-PCEVEp-b-PSiDEGVEq and PSiDEGVEq-b-PCEVEp-b-PnBVEn-b-PCEVEp-b-PSiDEGVEq terpolymers with high crossover efficiency, no PCEVE-induced physical gelation, predictable Mn and PDI < 1.15 were synthesized successfully provided that the targeted DPCEVE/DPnBVE ratio (i.e., p/n) did not exceed 2 and 0.2, respectively. The quantitative desilylation of the PSiEGVE by n-Bu4N+F- in THF at 0°C led to triblock and pentablock terpolymers in which the PCEVE is the central block and the polyalcohol is the outer block. The thermal properties of the synthesized materials were examined by differential scanning calorimetry.
    01/2015; 6(8). DOI:10.1039/C4PY01728E
  • Raju Francis · Deepa K. Baby · Yves Gnanou
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    ABSTRACT: Amphiphilic graft copolymers made of a Chitosan (CS) backbone and three arm polystyrene (PS) grafts were prepared by "grafting onto" strategy using Toluene Diisocyanate. IR spectroscopy and SEC show the successful grafting process. SEM pictures of Chitosan-g-Polystyrene (CS-g-PS) indicate a spherulite like surface and exhibit properties that result from the disappearance of Chitosan crystallinity. The introduced polystyrene star grafts units improve hydrophobic properties considerably as confirmed by the very high solubility of (CS-g-PS) in organic solvents. The graft copolymer which self-assembles into polymeric micelles in organic media demonstrates much better adsorption of transition and inner transition metal ions than pure Chitosan whose amine groups are not necessarily available due to crystallinity.
    Journal of Colloid and Interface Science 01/2015; 438. DOI:10.1016/j.jcis.2014.09.034 · 3.55 Impact Factor
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    ABSTRACT: A “catalyst switch” strategy has been used to sequentially polymerize four different heterocyclic monomers. In the first step, epoxides (1,2-butylene oxide and ethylene oxide) were successively polymerized from a monohydroxy or trihydroxy initiator in the presence of a strong phosphazene base promoter (t-BuP4). Then, an excess of diphenyl phosphate (DPP) was introduced, followed by addition and polymerization of a cyclic carbonate (trimethylene carbonate) and a cyclic ester (δ-valerolactone or ε-caprolactone). DPP acted as both neutralizer of the phosphazenium alkoxide (polyether chain end) and activator of the cyclic carbonate/ester. Using this method, linear- and star-tetrablock quarterpolymers were prepared in one pot. This work is emphasizing the strength of the previously developed catalyst switch strategy for the facile metal-free synthesis of complex macromolecular architectures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014
    Journal of Polymer Science Part A Polymer Chemistry 01/2015; 53(2). DOI:10.1002/pola.27332 · 3.54 Impact Factor
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    ABSTRACT: A novel strategy using polyhomologation and ring opening metathesis polymerization (ROMP) has been developed for the synthesis of well-defined polyethylene (PE) molecular brushes. Polyhomologation was used to afford an OH-terminated PE, which after transformation to the norbornyl PE macromonomer was subjected to ROMP. Kinetics of ROMP of the PE macromonomer was studied by in situ 1H NMR monitoring. The brush structure was proved from HT-GPC, 1H NMR and DSC results.
    08/2014; 5(22). DOI:10.1039/C4PY00815D
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    ABSTRACT: A “catalyst switch” strategy was used to synthesize well-defined polyether–polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts.
    Macromolecules 06/2014; 47(12):3814–3822. DOI:10.1021/ma500830v · 5.93 Impact Factor
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    ABSTRACT: Metal-free polymerization of ethylene oxide (EO) catalyzed by a relatively mild phosphazene base (t-BuP2) was proven feasible, which enabled the one-pot sequential polymerization of EO, ε-caprolactone, and L-lactide. Using either 3-phenyl-1-propanol or water as an initiator, the corresponding triblock or pentablock terpolymers were easily prepared.
    05/2014; 5(12). DOI:10.1039/C4PY00429A
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    ABSTRACT: The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation of carboxylic acid to hydroxyl ester, followed by slow chain growth together with simultaneous and fast end-group transesterification, which led to poly(ethylene oxide) (PEO) consisting of monoester (monohydroxyl), diester, and dihydroxyl species. An appropriate t-BuP4/acid ratio was proven to be essential to achieve better control over the polymerization and low dispersity of PEO. This work provides important information and enriches the toolbox for macromolecular and biomolecular engineering with protic initiating sites.
    Macromolecules 02/2014; 47(5):1693–1698. DOI:10.1021/ma500067j · 5.93 Impact Factor
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    ABSTRACT: Polyhomologation, recently developed by Shea, is a borane-initiated living polymerization of ylides leading to linear polymethylenes (C1 polymerization) with controlled molecular weight, low polydispersity, and well-defined structures. In this Review, the copolyhomologation of different ylides as well as the combination of polyhomologation with controlled/living (nitroxide-mediated, atom transfer radical, reversible addition-fragmentation chain-transfer) and living (ring opening, anionic) polymerizations is discussed.
    Macromolecular Rapid Communications 02/2014; 35(4). DOI:10.1002/marc.201300848 · 4.61 Impact Factor
  • Polimery -Warsaw- 01/2014; 59(01):49-59. DOI:10.14314/polimery.2014.049 · 0.62 Impact Factor
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    ABSTRACT: A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation.
    Chemical Communications 08/2013; 49(79). DOI:10.1039/c3cc44928a · 6.83 Impact Factor
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    ABSTRACT: The chemistry of N-heterocyclic carbenes (NHCs) has witnessed tremendous development in the past two decades: NHCs have not only become versatile ligands for transition metals, but have also emerged as powerful organic catalysts in molecular chemistry and, more recently, in metal-free polymer synthesis. To understand the success of NHCs, this review first presents the electronic properties of NHCs, their main synthetic methods, their handling, and their reactivity. Their ability to activate key functional groups (e.g. aldehydes, esters, heterocycles, silyl ketene acetals, alcohols) is then discussed in the context of molecular chemistry. Focus has been placed on the activation of substrates finding analogies with monomers (e.g. bis-aldehydes, multi-isocyanates, cyclic esters, epoxides, N-carboxyanhydrides, etc.) and/or initiators (e.g. hydroxy- or trimethylsilyl-containing reagents) employed in such "organopolymerisation" reactions utilizing NHCs. A variety of metal-free polymers, including aliphatic polyesters and polyethers, poly(α-peptoid)s, poly(meth)acrylates, polyurethanes, or polysiloxanes can be obtained in this way. The last section covers the use of NHCs as structural components of the polymer chain. Indeed, NHC-based photoinitiators, chain transfer agents or functionalizing agents, as well as bifunctional NHC monomer substrates, can also serve for metal-free polymer synthesis.
    Chemical Society Reviews 01/2013; 42(5). DOI:10.1039/c2cs35383k · 30.43 Impact Factor
  • Rachid Matmour · Yves Gnanou
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    ABSTRACT: This article reviews the various methods developed to generate di- and multicarbanionic lithiated initiators, the difficulties associated with their synthesis but also their potential in macromolecular engineering. It is shown that a wealth of complex macromolecular architectures based on monomers amenable to carbanionic polymerization can now be synthesized by divergent approach from these di- and multicarbanionic lithiated initiators. A comparison is made with other types of multifunctional initiators that have been developed from other living/controlled polymerizations, generating similar complex polymeric architectures from other monomers. A comparison is also made with the structures generated by the convergent carbanionic approach.
    Progress in Polymer Science 01/2013; 38(1):30–62. DOI:10.1016/j.progpolymsci.2012.08.003 · 26.85 Impact Factor
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    ABSTRACT: Anion metathesis of imidazol(in)ium chlorides with KHCO(3) afforded an easy one step access to air stable imidazol(in)ium hydrogen carbonates, denoted as [NHC(H)][HCO(3)]. In solution, these compounds were found to be in equilibrium with their corresponding imidazol(in)ium carboxylates, referred to as N-heterocyclic carbene (NHC)-CO(2) adducts. The [NHC(H)][HCO(3)] salts were next shown to behave as masked NHCs, allowing for the NHC moiety to be readily transferred to both organic and organometallic substrates, without the need for dry and oxygen-free conditions. In addition, such [NHC(H)][HCO(3)] precursors were successfully investigated as precatalysts in two selected organocatalyzed reactions of molecular chemistry and polymer synthesis, namely, the benzoin condensation reaction and the ring-opening polymerization of d,l-lactide, respectively. The generation of NHCs from [NHC(H)][HCO(3)] precursors occurred via the formal loss of H(2)CO(3)via a concerted low energy pathway, as substantiated by Density Functional Theory (DFT) calculations.
    Journal of the American Chemical Society 04/2012; 134(15):6776-84. DOI:10.1021/ja3005804 · 11.44 Impact Factor
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    ABSTRACT: A free N-heterocyclic carbene has been efficiently used for the organocatalysed step-growthpolymerisation between aliphatic diisocyanates and diols. Both the nature of the diisocyanate monomer and the order of addition of reactants are critical parameters for the successful synthesis of soluble linear polyurethanes.
    02/2012; 3(3):605-608. DOI:10.1039/C2PY00477A
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    ABSTRACT: Degradable dendrimer-like PEOs were designed using an original ABC-type branching agent featuring a cleavable ketal group, following an iterative divergent approach based on the anionic ring opening polymerization (AROP) of ethylene oxide and arborization of PEO chain ends. A seventh generation dendrimer-like PEO carrying 192 peripheral hydroxyls and exhibiting a molar mass of 446 kg · mol(-1) was obtained in this way. The chemical degradation of these dendritic scaffolds was next successfully accomplished under acidic conditions, forming linear PEO chains of low molar mass (≈2 kg · mol(-1)), as monitored by (1)H NMR, SEC, and MALDI-TOF mass spectrometry as well as by AFM.
    Macromolecular Rapid Communications 11/2011; 32(21):1722-8. DOI:10.1002/marc.201100459 · 4.61 Impact Factor

Publication Stats

5k Citations
761.65 Total Impact Points

Institutions

  • 2013–2015
    • King Abdullah University of Science and Technology
      • Division of Physical Sciences and Engineering (PSE)
      Djidda, Makkah, Saudi Arabia
  • 1998–2013
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1995–2012
    • Université Bordeaux 1
      • UMR LCPO - Laboratoire de Chimie des Polymères Organiques
      Talence, Aquitaine, France
  • 2011
    • Carnegie Mellon University
      • Department of Chemistry
      Pittsburgh, Pennsylvania, United States
  • 2000–2011
    • University of Bordeaux
      Burdeos, Aquitaine, France
  • 2010
    • Paul Sabatier University - Toulouse III
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2005–2007
    • Emory University
      • Department of Surgery
      Atlanta, Georgia, United States
    • University of Florida
      • Department of Chemistry
      Gainesville, Florida, United States
    • University of North Carolina at Chapel Hill
      • Department of Chemistry
      North Carolina, United States
  • 2003
    • Centre de Recherche Paul Pascal
      Pessac, Aquitaine, France
  • 2002
    • Université Bordeaux Montaigne
      Pessac, Aquitaine, France
  • 1998–2002
    • Universidad del País Vasco / Euskal Herriko Unibertsitatea
      Leioa, Basque Country, Spain
  • 2001
    • Laboratoire de Chimie de Coordination.
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1992
    • Massachusetts Institute of Technology
      • Department of Chemical Engineering
      Cambridge, Massachusetts, United States