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See detailDetermination of polyisoprene-block-poly(methyl methacrylate) domain sizes using 1H spin diffusion
Werkhoven, Thekla M; Mulder, Fokko M; Zune, Catherine et al

in Macromolecular Chemistry and Physics (2003), 204(1), 46-51

The microphase structure of polyisoprene-block-poly(methyl methacrylate) diblock copolymers was studied using solid-state NMR techniques. Wideline separation spectroscopy reveals a narrow interphase ... [more ▼]

The microphase structure of polyisoprene-block-poly(methyl methacrylate) diblock copolymers was studied using solid-state NMR techniques. Wideline separation spectroscopy reveals a narrow interphase between the two polymers. The domain sizes of a lamellar sample and a sample with hexagonally ordered cylinders were determined using 1H spin diffusion. The lamellar sample shows a domain size of 16 ± 2 nm for the minor polyisoprene phase and a long period of 33 ± 4 nm. The cylindrical structure has a long period of 38 ± 7 nm, the diameter of the PMMA cylinders is 21 ± 4 nm. These results are about 20% below the estimates obtained from theoretical calculations according to Helfand and Wasserman [less ▲]

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See detailEffect of the Solvent Polarity on the Living Ligated Anionic Polymerization of tert-Butyl Methacrylate and Copolymerization with Methyl Methacrylate
Zune, Catherine; Archambeau, C.; Dubois, Philippe ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2001), 39(10), 1774-1785

An anionic polymerization of t-butyl methacrylate and a copolymerization with methyl methacrylate were initiated with an organolithium ligated with 10 equiv of LiCl. As a rule, the complexation of the ... [more ▼]

An anionic polymerization of t-butyl methacrylate and a copolymerization with methyl methacrylate were initiated with an organolithium ligated with 10 equiv of LiCl. As a rule, the complexation of the active species by LiCl masked the effect that the polarity of the solvent might have on the molecular structure of the chains. [less ▲]

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See detailAnionic synthesis of cyclic anhydride end-capped poly(methyl methacrylate)
Fallais, Isabelle; Pantoustier, Nadège; Devaux, Jacques et al

in Polymer (2000), 41(14), 5535-5539

This paper reports on the anionic synthesis of poly(methyl methacrylate) chains end-capped by cyclic anhydride. The method is based on the chemical derivatization of a precursor tert-butyl diester end ... [more ▼]

This paper reports on the anionic synthesis of poly(methyl methacrylate) chains end-capped by cyclic anhydride. The method is based on the chemical derivatization of a precursor tert-butyl diester end-group. Compared to the thermal modification, which was previously used, this method allows intermolecular coupling and polymer degradation to be avoided. But up to now, the final anhydride content remains moderate and has still to be improved. [less ▲]

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See detailStudy of the propagation center in the anionic polymerization of (meth)acrylic monomers: NMR study of Di-tert-butyl 2-Lithio-2.4'-trimethylglutarate and living poly(tert-butyl methacrylate) oligomers in THF/toluene mixtures
Zune, Catherine; Dubois, Philippe ULg; Grandjean, Jean ULg et al

in Macromolecules (1999), 32(7), 5477-5486

Solvation influences both the stereoregularity and molecular weight distribution (MWD) of poly(tert-butyl methacrylate) (PtBMA) prepared by anionic polymerization of tBMA with a lithium counterion in THF ... [more ▼]

Solvation influences both the stereoregularity and molecular weight distribution (MWD) of poly(tert-butyl methacrylate) (PtBMA) prepared by anionic polymerization of tBMA with a lithium counterion in THF/toluene mixed solvents at −78 °C. As a probe of the structural changes of the propagating species, multinuclear 7Li, 1H, and 13C NMR analysis of di-tert-butyl 2-lithio-2,4,4‘-trimethylglutarate (a model dimer, A) and of short-length living PtBMA chains is reported and discussed. Whatever the system, the main structure of the lithium ester enolate in THF/toluene mixtures is similar to that one reported in THF. In the case of A and for toluene contents exceeding 50% v/v, partly organized pseudophases can additionally be detected in the 7Li NMR spectra, but they do not provide well-developed 1H and 13C NMR signals. The chemical shifts of 1H and 13C signals of A support the dimeric form of this model. An equilibrium between dimeric and nonaggregated living PtBMA chains has been previously proposed to dominate in pure THF. However, marked self-termination of low-molecular weight living oligomers prepared in THF/toluene mixtures can be observed at 263 K, in contrast to the stability observed in pure THF up to 298 K. Another contrasting feature is the broadening of the molecular weight distribution which can be explained by an aggregation process that stabilizes oligomers at the early stage of the anionic polymerization as supported by SEC-RI and SEC-UV eluograms. [less ▲]

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See detailAnionic polymerization of methacrylic monomers: characterization of the propagating species
Zune, Catherine; Jérôme, Robert ULg

in Progress in Polymer Science (1999), 24(5), 631-664

Ligation of the anionic species responsible for the polymerization (LAP) of alkyl(meth)acrylates has much contributed to improve polymerization control. This ligated anionic polymerization has been ... [more ▼]

Ligation of the anionic species responsible for the polymerization (LAP) of alkyl(meth)acrylates has much contributed to improve polymerization control. This ligated anionic polymerization has been firstly studied by using model compounds, such as low molecular weight lithium ester enolates. Recently, effort has been devoted to the direct analysis of the species that propagate the anionic polymerization of (meth)acrylates. In addition to IR, multinuclear NMR spectroscopy has been very instrumental in the elucidation of the structure and aggregation of the active species and how these characteristic features are modified by the addition of various types of ligands. This substantial progress in the characterization of the polyalkyl(meth)acrylate anions, ligated or not, is reported in this review. [less ▲]

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See detailAnionic polymerization of (meth)acrylic monomers: anionic polymerization of tert-butyl methacrylate in toluene
Zune, Catherine; Dubois, Philippe ULg; Jérôme, Robert ULg

in Polymer International (1999), 48(7), 565-570

The anionic polymerization of tBMA initiated by an organolithium compound in toluene at low temperature (-78 °C and 0 °C) has been revisited. Under these experimental conditions, no livingness is reported ... [more ▼]

The anionic polymerization of tBMA initiated by an organolithium compound in toluene at low temperature (-78 °C and 0 °C) has been revisited. Under these experimental conditions, no livingness is reported, consistently with formation of an important fraction of oligomers (Mn = 650). [less ▲]

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See detailAnalysis of living tert-butyl methacrylate oligoanions in tetrahydrofuran by NMR spectroscopy, viscosity and light scattering
Zune, Catherine; Dubois, Philippe; Grandjean, Jean ULg et al

in Macromolecular Chemistry and Physics (1999), 200(3), 562-573

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by ... [more ▼]

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by viscosimetry, light scattering and gradient field NMR techniques in a range of temperature from 253 K to 298 K. These techniques have been systematically used for the analysis of both the living oligomers and the same chains recovered after hydrolysis of the anionic end groups. The structure of the growing anionic species was analyzed by means of 13C and 7Li NMR spectroscopy. 13C NMR required the selective labeling of the last monomer units by 13C atoms. [less ▲]

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See detailRecent achievements in anionic polymerization of (meth)acrylates
Jérôme, Robert ULg; Teyssié, Philippe; Vuillemin, Bruno et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(1), 1-10

The constant progress of the anionic polymerization of (meth)acrylates is discussed from both the fundamental and practical points of view. A special attention is paid to the improved macromolecular ... [more ▼]

The constant progress of the anionic polymerization of (meth)acrylates is discussed from both the fundamental and practical points of view. A special attention is paid to the improved macromolecular engineering of (meth)acrylate-based (co)polymers. The resulting most important materials and the scaling-up process needed for their production are also emphasized. The recent developments witness for the healthy state of the anionic polymerization of these polar monomers. [less ▲]

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See detailNew initiator system for the anionic polymerization of (meth)acrylates in toluene. IV. Random copolymerization of (meth)acrylates in toluene initiated by s-Buli ligated by lithium silanolates
Zune, Catherine; Zundel, Thomas; Dubois, Philippe ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(14), 2525-2535

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initiated in toluene by a mixed complex of lithium silanolate (s-BuMe2SiOLi) and s-BuLi (molar ratio > 21) formed in situ by reaction ... [more ▼]

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initiated in toluene by a mixed complex of lithium silanolate (s-BuMe2SiOLi) and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with hexamethylcyclotrisiloxane (D3). Fully acrylate and methacrylate copolymers, i.e., poly(methyl acrylate-co-n-butyl acrylate), poly(methyl methacrylate-co-ethyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate) of a rather narrow molecular weight distribution have been synthesized. However, copolymerization of alkyl acrylate and methyl methacrylate pairs has completely failed, leading to the selective formation of homopoly(acrylate). As result of the isotactic stereoregulation of the alkyl methacrylate polymerization by the s-BuLi/s-BuMe2SiOLi initiator, highly isotactic random and block copolymers of (alkyl) methacrylates have been prepared and their thermal behavior analyzed. The structure of isotactic poly(ethyl methacrylate-co-methyl methacrylate) copolymers has been analyzed in more detail by Nuclear Magnetic Resonance (NMR). [less ▲]

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See detailAnionic synthesis of [1,4-poly(diene)-b-syndiotactic poly(methyl methacrylate)] diblock copolymers: 7Li NMR study of the intermediate reaction of lithium poly(diene) anion with 1,1-diphenylethylene
Zune, Catherine; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecular Chemistry and Physics (1999), 200(2), 460-467

The end-capping with 1,1-diphenylethylene (DPE) of living 1,4-poly(diene) lithiated anions prepared in cyclohexane (Chx) and toluene is a major but poorly controlled step in the synthesis of syndiotactic ... [more ▼]

The end-capping with 1,1-diphenylethylene (DPE) of living 1,4-poly(diene) lithiated anions prepared in cyclohexane (Chx) and toluene is a major but poorly controlled step in the synthesis of syndiotactic poly(methyl methacrylate) (sPMMA) containing block copolymers. The kinetics of the reaction have been studied by means of 7Li NMR not only in Chx and toluene but also in their mixtures with polar solvents, since the solvent polarity must be increased for MMA to be predominantly converted into sPMMA. Although the addition of a polar solvent (tetrahydrofuran (THF), diethyl ether) to Chx and toluene is known to increase the reactivity of living polymeric anions, contaminating lithium salts, such as lithium hydroxide, slow down the end-capping reaction even when 10 vol.-% polar solvent is added. Moreover, the polymeric diphenylalkyllithium anions are unstable in 1/9 (v/v) THF/Chx mixture, as a result of the nucleophilic attack of THF. On the basis of all these observations, new experimental conditions are proposed for improving the control of the anionic block copolymerization of 1,3-dienes and MMA to yield 1,4-poly(diene) and sPMMA containing block copolymers. [less ▲]

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See detailNew ligands for the living isotactic anionic polymerization of methyl methacrylate in toluene at 0°C. 2. 7Li NMR analysis of sec-butyllithium ligated by lithium silanolates
Zundel, Thomas; Zune, Catherine; Teyssié, Philippe et al

in Macromolecules (1998), 31(13), 4089-4092

The mixed associated species {xsBuLi, (y − x)sBuMe2SiOLi} formed by reaction of sec-Butyllithium (sBuLi) with octamethylcyclotetrasiloxane (Me2SiO)4 in toluene have been used to initiate the anionic ... [more ▼]

The mixed associated species {xsBuLi, (y − x)sBuMe2SiOLi} formed by reaction of sec-Butyllithium (sBuLi) with octamethylcyclotetrasiloxane (Me2SiO)4 in toluene have been used to initiate the anionic polymerization of methyl methacrylate (MMA) in that solvent at 0 °C. The active species generated by this new type of initiator have been characterized by 7Li NMR at 0 °C. The 7Li NMR spectra of sBuLi and sBuMe2SiOLi mixtures in toluene show that only one single type of {sBuLi, 5sBuMe2SiOLi} mixed species prevails at [sBuMe2SiOLi]/[sBuLi] molar ratios higher than ca. 21, as result of a large excess of {6sBuMe2SiOLi} species. The 7Li NMR has also concluded to the formation of {PMMALi, 5sBuMe2SiOLi} species upon the addition of MMA to that initiator solution, supporting the theory that only one type of ionic species is active during the MMA conversion. These active centers are stable for at least 1 h at 0 °C as confirmed by 7Li NMR. [less ▲]

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See detailStudy of the propagation center in the anionic polymerization of (meth)acrylic monomers: NMR and MO LCAO study of the interaction of Di-tert-butyl 2-lithio-2,4,4-trimethylglutarate and the living poly(tert-butyl methacrylate) oligomers with lithium 2-(2-methoxyethoxy)ethoxide in tetrahydrofuran
Zune, Catherine; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1998), 31(9), 2731-2743

Interactions of lithium 2-(2-methoxyethoxy)ethoxide (LiOEEM) with the model dimer di-tert-butyl 2-lithio-2,4,4-trimethylglutarate (A) and the living poly(tert-butyl methacrylate) oligomers (B) were ... [more ▼]

Interactions of lithium 2-(2-methoxyethoxy)ethoxide (LiOEEM) with the model dimer di-tert-butyl 2-lithio-2,4,4-trimethylglutarate (A) and the living poly(tert-butyl methacrylate) oligomers (B) were studied in tetrahydrofuran-d8 at 203−273 K using 1H, 13C, 7Li, and 6Li, 1D and 2D, NMR and ab initio SCF 3-21G and MNDO quantum chemical calculations. LiOEEM is shown to have a strong tendency to self-aggregation, producing dimeric, trimeric, and tetrameric aggregates and competing with its mixed aggregation (or complexation) with A and, in particular, B. When dissolved in THF, LiOEEM as well as its mixtures with A form metastable systems which relax in several days at 258 K into equilibrium. Interaction of LiOEEM with A leads to a system of mixed aggregates LiOEEM1A1, LiOEEM3A1, and possibly LiOEEM2A1 along with the original components, in relative populations depending on the LiOEEM/A molar ratio, temperature, time, and probably other factors of preparation. Probable structures of these complexes are proposed, and the nature of the prevalent bonding is suggested. Experimental results indicate that LiOEEM is unable to convert A completely at moderate excess (up to 4/1 mol/mol). Interaction of LiOEEM with B leads to quite analogous complexes but with even lower yields. There appear to be traces of uncomplexed B even at the LiOEEM/B ratio of 10 mol/mol. This is suggested to produce at least two different kinds of active growth centers in the corresponding ligated anionic polymerization of tert-butyl methacrylate and, consequently, the observed bimodality of the polymeric product. The difference with respect to methyl methacrylate, where LiOEEM ensures an almost ideal living polymerization, is suggested to be due to the steric hindrance of efficient complexation exerted by the tert-butyl group. [less ▲]

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See detailStudy of the propagation center in the anionic polymerization of (meth)acrylic monomers: NMR and MNDO study of the complexes of Di-tert-butyl 2-lithio-2,4,4-trimethylglutarate and of the living poly(tert-butyl methacrylate) oligomers with lithium chloride
Zune, Catherine; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1998), 31(9), 2744-2755

Interactions of living oligomers of tert-butyl methacrylate (tBuMA) with a Li counterion and of the model living dimer di-tert-butyl 2-lithio-2,4,4-trimethylglutarate (A) with LiCl (B) were studied in ... [more ▼]

Interactions of living oligomers of tert-butyl methacrylate (tBuMA) with a Li counterion and of the model living dimer di-tert-butyl 2-lithio-2,4,4-trimethylglutarate (A) with LiCl (B) were studied in tetrahydrofuran-d8 (THF-d8) solution by 7Li, 6Li, 1H, and 13C, 1D and 2D, NMR spectroscopy. Di-tert-butyl 2-lithio-2,4,4-trimethylglutarate is shown to form a 1:1 complex with lithium chloride in THF. 1H, 7Li NMR results suggest that a rapid equilibrium between free LiCl and the mixed complex takes place when the molar ratio LiCl:lithiated dimer is higher than 1. From 13C relaxation times, a dimeric aggregation (i.e. A2B2) of the complex is deduced, in full accord with MNDO calculations. Preliminary results are presented for living tBuMA oligomers prepared by initiation with diphenylhexyllithium in the presence of various amounts of lithium chloride. Fast-acquired 13C NMR spectra of the living ends were recorded using 13C-enriched monomer added at the end of the polymerization. Their structure is shown to be affected by the amount of LiCl added and to correspond to an equilibrium between free lithium chloride and a complexed end group. A higher excess of LiCl apparently does not change the nature of the complexed living end. The oligomers exhibit marked self-termination in THF at 273 K. Finally, a correlation of the structure of the living chain ends with the macromolecular parameters of the resulting polymer is attempted. [less ▲]

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