References of "Moineau, Georges"
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See detailSynthesis of fully acrylic thermoplastic elastomers by atom transfer radical polymerization (ATRP), 2a effect of the catalyst on the molecular control and the rheological properties of the triblock copolymers
Moineau, Georges; Minet, Michaël; Teyssié, Philippe et al

in Macromolecular Chemistry and Physics (2000), 201(11), 1108-1114

The ATRP of MMA was initiated by α,ω-dibromo poly(n-butyl acrylate) in the presence of NiBr2(PPh3)2 leading to poly(MMA)-b-poly(nBuA)-b-poly(MMA) triblock copolymers (MnBM). The initiation of the MMA ... [more ▼]

The ATRP of MMA was initiated by α,ω-dibromo poly(n-butyl acrylate) in the presence of NiBr2(PPh3)2 leading to poly(MMA)-b-poly(nBuA)-b-poly(MMA) triblock copolymers (MnBM). The initiation of the MMA polymerization is slow compared to the chain propagation, which results in PMMA blocks of broad molecular weight distribution (MWD). In order to improve this situation, several experimental parameters were varied. CuBr/dNBipy was first substituted for NiBr2(PPh3)2, the results being, however, even worse. Then, the halide exchange was considered by substituting CuCl for CuBr. The CuCl/dNBipy catalyst proved superiority over the originally used NiBr2(PPh3)2 system. Finally, the addition of an excess of CuCl2 (deactivator) to the CuCl/dNBipy catalyst was very beneficial in decreasing the MWD of the PMMA blocks. Indeed, the SEC chromatograms are monomodal and narrow from the very beginning of the polymerization. The rheological analysis of the MnBM triblocks synthesized in the presence of each of the aforementioned catalytic systems confirmed differences in the molecular control of the copolymeriza-tion reaction. [less ▲]

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See detailSynthesis, morphology, and mechanical properties of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly (methyl methacrylate) triblocks. Ligated anionic polymerization vs atom transfer radical polymerization
Tong, Jiang-Dong; Moineau, Georges; Leclère, Philippe et al

in Macromolecules (2000), 33(2), 470-479

Poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblock copolymers have been prepared by ligated anionic polymerization (LAP; 8K-50K-8K) and atom transfer radical ... [more ▼]

Poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblock copolymers have been prepared by ligated anionic polymerization (LAP; 8K-50K-8K) and atom transfer radical polymerization (ATRP; 9K-51K-9K). Size exclusion chromatography, nuclear magnetic resonance, and differential scanning calorimetry have confirmed that the molecular structure of the two triblock copolymers is essentially identical. However, important differences are found in dynamic mechanical properties, viscoelastic properties, and stress−strain behavior. Indeed, the ATRP copolymer has low storage modulus, high complex viscosity, high order−disorder transition temperature, and poor ultimate tensile strength and elongation at break, compared to those of the LAP analogue. Marked differences also observed by tapping mode atomic force microscopy in the microscopic morphology of thin films of these copolymers. All these observations can be explained by the slow initiation of MMA by the poly(n-butyl acrylate) macroinitiator used in ATRP in contrast to what happens when MMA is added to living poly(tert-butyl acrylate) anions. As a result, the polydispersity of the short poly(methyl methacrylate) (PMMA) outer blocks is much broader in the ATRP copolymer, although the polydispersity index of the triblock is only 1.15. This heterogeneous structure of the ATRP triblock is also supported by the comparison of homo-PMMAs prepared by LAP and ATRP. [less ▲]

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See detailSynthesis and characterization of poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) copolymers by two-step controlled radical polymerization (ATRP) catalyzed by NiBr2(PPh3)2, 1+
Moineau, Georges; Minet, Michaël; Teyssié, Philippe et al

in Macromolecules (1999), 32(25), 8277-8282

Poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MnBM) have been synthesized by the sequential controlled radical polymerization (atom transfer ... [more ▼]

Poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MnBM) have been synthesized by the sequential controlled radical polymerization (atom transfer radical polymerization, ATRP) of n-butyl acrylate (n-BuA) followed by methyl methacrylate (MMA). The polymerization of n-BuA has been first initiated by the difunctional (diethyl meso-2,5-dibromoadipate) initiator in the presence of the NiBr2(PPh3)2 catalyst. After isolation, the α,ω-dibromo poly(n-butyl acrylate) chains have been used as macroinitiators for the polymerization of either n-BuA or MMA leading to chain extension or to the desired triblock copolymers, respectively. The kinetic study of the two-step process has shown that the initiation of the MMA polymerization by the poly(n-BuA) macroinitiator is slow and leads to PMMA outer blocks of broad polydispersity. Differential scanning calorimetry (DSC) and dynamical mechanical analysis (DMA) have confirmed the two-phase morphology of the triblocks. Finally, DMA and tensile testing of these copolymers have emphasized poor mechanical properties in possible relation to the broad polydispersity of the PMMA outer blocks. [less ▲]

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See detailDirect observation of microdomain morphology in "all-acrylic" thermoplastic elastomers synthesized via living radical polymerization
Leclère, Philippe; Moineau, Georges; Minet, Michaël et al

in Langmuir (1999), 15(11), 3915-3919

We investigate the microscopic morphology of thin films of symmetric triblock copolymers synthesized via a two-step “living” radical polymerization of n-butylacrylate and methyl methacrylate. These ... [more ▼]

We investigate the microscopic morphology of thin films of symmetric triblock copolymers synthesized via a two-step “living” radical polymerization of n-butylacrylate and methyl methacrylate. These copolymers with low poly(methyl methacrylate) contents constitute a new class of potential thermoplastic elastomers with higher service temperature and oxidation resistance compared to conventional polydiene−polystyrene-based thermoplastic elastomers. The straightforward synthetic pathway allows for strict control of molecular weight, molecular-weight distribution, and composition. The presence in the copolymer of immiscible segments covalently bound to each other leads to phase separation on the nanometer scale. Regular organization of the phase-separated nanodomains is observed in real space by scanning force microscopy. The data point to a strong contrast in the local mechanical properties, corresponding to the microphase morphology. Cylinders of the minority phase are found to orient perpendicular to the surface, because of the surface energy difference between the constituents. Lamellae are also arranged perpendicular to the surface, in contrast to what is usually observed in block copolymers. This particular orientation is thought to result from the symmetric character of these triblock systems, with the outer blocks more polar than the central sequence. [less ▲]

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See detailControlled radical polymerization of (meth)acrylates by ATRP with NiBr2(PPh3)2 as catalyst
Moineau, Georges; Minet, Michaël; Dubois, Philippe ULg et al

in Macromolecules (1999), 32(1), 27-35

NiBr2(PPh3)2 has been found to be an efficient catalyst for the ATRP of methyl methacrylate (MMA) and n-butyl acrylate (n-BuA) initiated by an alkyl halide in the absence of any activator (e.g., Lewis ... [more ▼]

NiBr2(PPh3)2 has been found to be an efficient catalyst for the ATRP of methyl methacrylate (MMA) and n-butyl acrylate (n-BuA) initiated by an alkyl halide in the absence of any activator (e.g., Lewis acid) at 85 °C. The molecular weight distribution of the poly(meth)acrylates is narrow (Mw/Mn = 1.1−1.4). However, some side reactions (more likely coupling reactions) are observed at high monomer conversions in the case of n-BuA. An excess of PPh3 has proved to increase the polymerization rate of MMA while preserving the control of the molecular parameters. When the catalyst/initiator molar ratio is too small (e.g., 0.05), the polymerization rate decreases, the polydispersity increases, and the initiation is less efficient. α-Acid and α-hydroxyl end groups have been successfully attached to the chains by using functional initiators, such as 2-bromo-2-methylpropionic acid and 2,2‘,2‘ ‘-tribromoethanol. Reactivity ratios for the MMA/n-BuA comonomer pair have been measured and found to be close to the values observed for a conventional free-radical polymerization. Diethyl meso-2,5-dibromoadipate has been used as a difunctional initiator for the n-BuA polymerization, leading to α,ω-bromo-poly(n-BuA) of narrow molecular weight distribution. Finally, the thermal stability of PMMA is consistent with the lack of termination reactions, while Tg is as high as 125 °C. [less ▲]

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See detailSimultaneous dual living polymerizations: a novel one-step approach to block and graft copolymers
Mecerreyes, David; Moineau, Georges; Dubois, Philippe ULg et al

in Angewandte Chemie (International ed. in English) (1998), 37(9), 1274-1276

Just one step is required for the synthesis of block copolymers by simultaneous living/controlled ring-opening and radical polymerization initiated by a difunctional (A-B) compound (shown schematically on ... [more ▼]

Just one step is required for the synthesis of block copolymers by simultaneous living/controlled ring-opening and radical polymerization initiated by a difunctional (A-B) compound (shown schematically on the right). [less ▲]

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See detailDual living free radical and ring opening polymerizations from a double-headed initiator
Hawker, Craig J; Hedrick, James L; Malmström, Eva E et al

in Macromolecules (1998), 31(2), 213-219

The concept of performing dual living polymerizations from a single initiating molecule with no intermediate activation, or transformation, steps is presented. The compatibility of “living”, or controlled ... [more ▼]

The concept of performing dual living polymerizations from a single initiating molecule with no intermediate activation, or transformation, steps is presented. The compatibility of “living”, or controlled free radical procedures, either nitroxide mediated or atom transfer radical polymerization (ATRP), with the living ring opening polymerization of ε-caprolactone, and vice versa, is demonstrated by the synthesis of a variety of well-defined block copolymers. For example, from a hydroxy-functionalized alkoxyamine, either the living ring opening polymerization of ε-caprolactone, or the “living” free radical polymerization of styrene can be performed leading to narrow polydispersity polymeric initiators. These polymeric initiators can then be used to initiate the living polymerization of the other monomer system without the need for intermediate steps. In a similar way, hydroxy-functionalized ATRP initiators can be used as bifunctional initiators for the polymerization of both ε-caprolactone and a variety of other vinyl monomers. The novel block copolymers that are obtained were shown to have low polydispersities and controllable molecular weights for both of the blocks. [less ▲]

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See detailControlled radical polymerization of methyl methacrylate initiated by an alkyl halide in the presence of the Wilkinson catalyst
Moineau, Georges; Granel, Claude; Dubois, Philippe ULg et al

in Macromolecules (1998), 31(2), 542-544

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