References of "De Winter, Julien"
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See detailHalomethyl-cobalt(bis-acetylacetonate) for the controlled synthesis of functional polymers
Demarteau, Jérémy ULg; Kermagoret, Anthony; German, Ian et al

in Chemical Communications (2015), 51(76), 14334-14337

Novel organocobalt complexes featuring weak C–CoL2 bonds (L = acetylacetonate) are prepared and used as sources of halomethyl radicals. They permit the precision synthesis of a-halide functionalized and ... [more ▼]

Novel organocobalt complexes featuring weak C–CoL2 bonds (L = acetylacetonate) are prepared and used as sources of halomethyl radicals. They permit the precision synthesis of a-halide functionalized and telechelic polymers in organic media or in water. Substitution of halide by azide allows derivatization of polymers using the CuAAC click reaction. [less ▲]

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See detailNovel organocobalt for the synthesis of functional polymers
Demarteau, Jérémy ULg; Kermagoret, Anthony; Jérôme, Christine ULg et al

Poster (2015, September 11)

Organocobalt(III) with acetylacetonate (acac) ligands is the most representative example of R-Co bearing a labile C-Co bond that can release alkyl radicals under mild experimental conditions without ... [more ▼]

Organocobalt(III) with acetylacetonate (acac) ligands is the most representative example of R-Co bearing a labile C-Co bond that can release alkyl radicals under mild experimental conditions without requiring a photoactivation. The unique isolated R-Co is a short oligo(vinyl acetate) end-capped by Co(acac)2. The high lability of its C-Co bond combined to the unique capacity of Co(acac)2 to reversibly trap alkyl radicals make this R-Co unique for the precision design of unprecedented polymers by Cobalt-Mediated Radical Polymerization (CMRP). The growth of unstabilized and highly reactive growing radicals formed by the addition of R• to unconjugated vinyl monomers (vinyl esters, vinyl amides, vinyl imidazolium, vinyl chloride, etc;) is controlled by the reversible formation of a weak C-Co bond at the polymer chain end. The lack of alternatives to this R-Co, especially to the structure of the alkyl group, has however placed limitations on post-functionalizations of end-chains. Other functional variants that would enable attractive chain-end derivatizations are unfortunately not available. In this poster, we will address this important challenge by describing an innovative synthetic route towards the preparation of new functional R-Co(acac)2 that are sources of halomethyl radicals under mild experimental conditions. The efficiency of these novel organocobalt complexes for the precision synthesis of end-functional and telechelic polymers will be described. Also, the solubility of these complexes in water enables the facile production of end-functionalized water soluble poly(ionic liquid)s. Further derivatizations of the halomethyl group at the chain-end of polymers produced by this system will be demonstrated by click reaction, largely broadening the range of possible functional groups. Finally, besides numerous applications in macromolecular engineering, this unexplored family of R-Co presents a high potential in radical reactions in organic synthesis by the facile production of halomethyl radicals. [less ▲]

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See detailNitroxide mediated polymerization of methacrylates at moderate temperature
Detrembleur, Christophe ULg; Jérôme, Christine ULg; De Winter, Julien et al

in Polymer Chemistry (2014), 5(2), 335-340

In this communication we report the first homopolymerization of a variety of methacrylates by an NMP process at moderate temperature (40–50 °C), using an easily accessible and inexpensive nitroxide ... [more ▼]

In this communication we report the first homopolymerization of a variety of methacrylates by an NMP process at moderate temperature (40–50 °C), using an easily accessible and inexpensive nitroxide precursor. The combination of a low temperature azo-initiator with a hindered nitroso-compound produces a mixture of hindered nitroxides in the polymerization medium that act as efficient polymerization control agents. Results of Electron Spin Resonance (ESR) spectroscopy experiments combined with mass spectrometric studies support the proposed in situ NMP mechanism. The hindered structure of the nitroxides formed in situ is believed to be responsible for the efficiency of the process by allowing it to proceed at low temperature, therefore limiting the side reactions generally observed in NMP of methacrylates. [less ▲]

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See detailThermally induced coupling of poly(thiophene)-based block copolymers prepared by Grignard metathesis polymerization: a straightforward route toward highly regioregular multiblock conjugated copolymers
Ouhib, Farid ULg; Desbief, Simon; Lazzaroni, Roberto et al

in Macromolecules (2012), 45(17), 6796-6806

We report on a convenient and simple process to prepare highly regioregular poly(thiophene)-based multiblock copolymers by a novel thermally induced coupling reaction. Diblock copolymers of 3 ... [more ▼]

We report on a convenient and simple process to prepare highly regioregular poly(thiophene)-based multiblock copolymers by a novel thermally induced coupling reaction. Diblock copolymers of 3-hexylthiophene (3HT) and 2,5-dibromo-3-(2-(2-tetrahydropyranyl-2-oxy)ethyl)thiophene (THPET) end-capped by a nickel complex (Br-P3HT-b-PTHPET-Ni(dppp)Br) are first prepared using Ni(dppp)Cl2 as catalyst at 30 °C by Grignard metathesis polymerization (GRIM process). The coupling of these α-bromo, ω-Ni(dppp)Br telechelic diblock copolymers then occurs by heating the solution of the copolymer at 80 °C for a few hours without adding any additional reagent. Reactions are complete in only 10 min when heating the copolymer at 120 °C using microwaves. The deprotection of the alcohol groups of PTHPET blocks allows further modifications such as the incorporation of acrylates by esterification. AFM analysis on thin films shows the influence of the nature of side chains (protected alcohol or acrylate), the molecular weight, and the architecture (diblock or multiblock) of the copolymer on the supramolecular organization of the polythiophene chains. [less ▲]

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See detailTailor-made polymers by cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Hurtgen, Marie ULg; De Winter, Julien et al

Poster (2010, May 25)

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See detailEffective cobalt-mediated radical coupling (CMRC) of poly(vinylacetate) and poly(N-vinylpyrrolidone) (co)polymer precursors
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

in Macromolecules (2010), 43(6), 2801-2813

Cobalt-mediated radical coupling (CMRC) is successfully applied to poly(vinyl acetate) (PVAc) and poly(N-vinylpyrrolidone) (PNVP) precursors for the first time. The coupling process is based on addition ... [more ▼]

Cobalt-mediated radical coupling (CMRC) is successfully applied to poly(vinyl acetate) (PVAc) and poly(N-vinylpyrrolidone) (PNVP) precursors for the first time. The coupling process is based on addition of isoprene onto polymer chains preformed by controlled radical polymerization with cobalt complexes (CMRP). The extents of coupling were high (>90%) to moderate (75-80%) for PVAc and PNVP precursors, respectively. Effects of the length of the polymer precursors and conditions used in the polymerization step on the coupling efficiency are discussed. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) analyses conducted on the coupling products demonstrate the preferential insertion of two isoprene units in the final polymers. The CMRC mechanistic proposal, supported by DFT calculations, is based on this microstructure feature. Finally, illustration of the macromolecular engineering potential of this technique is given by the preparation of symmetrical PVAc-b-PNVP-b-PVAc triblock copolymers starting from the corresponding PVAc-b-PNVP-[Co] diblock copolymer. [less ▲]

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See detailCobalt mediated radical coupling (CMRC) : an unusual route to midchain-functionalized symmetrical macromolecules
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

in Chemistry : A European Journal (2010), 16(5), 1799-1811

Cobalt-mediated radical coupling (CMRC) is a straightforward approach to the synthesis of symmetrical macromolecules that relies on the addition of 1,3-diene compounds onto polymer precursors preformed by ... [more ▼]

Cobalt-mediated radical coupling (CMRC) is a straightforward approach to the synthesis of symmetrical macromolecules that relies on the addition of 1,3-diene compounds onto polymer precursors preformed by cobalt-mediated radical polymerization (CMRP). Mechanistic features that make this process so efficient for radical polymer coupling are reported here. The mechanism was established on the basis of NMR spectroscopy and MALDI-MS analyses of the coupling product and corroborated by DFT calculations. A key feature of CMRC is the preferential insertion of two diene units in the middle of the chain of the coupling product mainly according to a trans-1,4-addition pathway. The large tolerance of CMRC towards the diene structure is demonstrated and the impact of this new coupling method on macromolecular engineering is discussed, especially for midchain functionalization of polymers. It is worth noting that the interest in CMRC goes beyond the field of polymer chemistry, since it constitutes a novel carbon-carbon bond formation method that could be applied to small organic molecules. [less ▲]

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See detailCobalt-mediated radical polymerization (CMRP) and coupling reaction (CMRC): mechanistic advances ans synthetic opportunities
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

Poster (2009, December 14)

Detailed reference viewed: 34 (10 ULg)