References of "Macromolecules"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailTuning of the morphology of core-shell-corona micelles in water. I. Transition from sphere to cylinder
Lei, Liangcai; Gohy, Jean-François; Willet, Nicolas ULg et al

in Macromolecules (2004), 37(3), 1089-1094

Poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) ABC triblock copolymers commonly form core-shell-corona (CSC) micelles in water. These micelles consist of a PS ... [more ▼]

Poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) ABC triblock copolymers commonly form core-shell-corona (CSC) micelles in water. These micelles consist of a PS spherical core, a P2VP shell, and a PEO corona. However, when the micelles are formed in the presence of a solvent selective for the PS block (benzene), the micellar morphology exhibits a sphere-to-rod transition, as result of the increased volume fraction of the core-forming blocks. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirm that a PS rod-like core is surrounded by a P2VP shell and an external PEO corona. Nevertheless, the rod-like micelles coexist with spherical micelles that should be thermodynamically less stable, because of a higher stretching of the PS chains in the core. The P2VP chains are also in a stretched conformation, whatever the pH. The P2VP shell has been used as nanoreactor for the production of gold nanoparticles. [less ▲]

Detailed reference viewed: 44 (2 ULg)
Full Text
Peer Reviewed
See detailPolymerization of epsilon-caprolactone initiated by Y alkoxide grafted onto porous silica
Martin, Eric; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecules (2003), 36(19), 7094-7099

Ring-opening polymerization of c-caprolactone has been initiated by Y isopropoxide grafted onto silica, in the presence of 2-propanol, in toluene at 40degreesC. The degree of polymerization is controlled ... [more ▼]

Ring-opening polymerization of c-caprolactone has been initiated by Y isopropoxide grafted onto silica, in the presence of 2-propanol, in toluene at 40degreesC. The degree of polymerization is controlled by the initial monomer/(alcohol + alkoxide) molar ratio. Deactivation of the chains by an alcohol is essential for them to be detached from the support and to be collected totally free of metal and silica residues. The alkoxide is also regenerated at the surface of the support, which allows for recycling the catalyst. [less ▲]

Detailed reference viewed: 11 (3 ULg)
Full Text
Peer Reviewed
See detailIn situ formation of yttrium alkoxides: A versatile and efficient catalyst for the ROP of epsilon-caprolactone
Martin, Eric; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecules (2003), 38(16), 5934-5941

[Tris(hexamethyldisilyl)amide] yttrium is a catalyst for the controlled ring-opening polymerization of epsilon-caprolactone when reacted with an excess of alcohol. Up to an alcohol-to-yttrium molar ratio ... [more ▼]

[Tris(hexamethyldisilyl)amide] yttrium is a catalyst for the controlled ring-opening polymerization of epsilon-caprolactone when reacted with an excess of alcohol. Up to an alcohol-to-yttrium molar ratio of 50, the chain transfer to the alcohol is quantitative, and the molecular weight of the chains can be predicted from the monomer-to-alcohol molar ratio. At alcohol-to-yttrium ratios higher than 100, the alcohol is quantitatively consumed provided that 1,1,1,3,3,3-hexamethyldisilazane, which is formed as a byproduct, is removed from the reation medium. Depending on the structure of the alcohol, end-functional polyesters can be prepared (e.g., with N-pyrrolyl and 3-thienyl end groups). Well-defined block and random copolymers of epsilon-CL with lactides and gamma-bromo-epsilon-caprolactone, respectively, have also been synthesized. Compared to aluminum alkoxides, the in situ formed yttrium alkoxides have the advantage of a much faster polymerization kinetics while preserving control. [less ▲]

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailPolymer coating of steel by a combination of electrografting and atom-transfer radical polymerization
Claes, Michaël; Voccia, Samuel; Detrembleur, Christophe ULg et al

in Macromolecules (2003), 36(16), 5926-5933

Cathodic electrografting of poly(2-chloropropionate ethyl acrylate) (poly[cPEA]) onto steel followed by the styrene grafting-from by atom transfer radical polymerization (ATRP) is an efficient strategy to ... [more ▼]

Cathodic electrografting of poly(2-chloropropionate ethyl acrylate) (poly[cPEA]) onto steel followed by the styrene grafting-from by atom transfer radical polymerization (ATRP) is an efficient strategy to impart strong adhesion to polystyrene films onto the electrically conductive substrate. Electrografting of poly(cPEA) chains at an appropriate potential and persistence of the activated chloride in the grafted chains were confirmed by XPS. Polystyrene deposition by ATRP with a ruthenium-based catalyst was analyzed by scanning electron microscopy and Raman spectroscopy. Adhesion of the polystyrene layer to the substrate is so strong that it cannot be detached by standard Scotch brand tapes. Moreover, local thermal analysis showed a loss of mobility for the PS chains tethered at the surface. [less ▲]

Detailed reference viewed: 37 (5 ULg)
Full Text
Peer Reviewed
See detailSynthesis and characterization of random copolyesters of epsilon-caprolactone and 2-oxepane-1,5-dione
Latere Dwan'Isa, Jean-Pierre; Lecomte, Philippe ULg; Dubois, Philippe ULg et al

in Macromolecules (2003), 36(8), 2609-2615

2-Oxepane-1,5-dione (OPD) has been synthesized by the Baeyer-Villiger oxidation of 1,4-cyclohexanedione and copolymerized with epsilon-caprolactone. This random copolymerization has been initiated by ... [more ▼]

2-Oxepane-1,5-dione (OPD) has been synthesized by the Baeyer-Villiger oxidation of 1,4-cyclohexanedione and copolymerized with epsilon-caprolactone. This random copolymerization has been initiated by different metal derivatives, i.e., tin octanoate, dibutyltin dimethoxide, and aluminum isopropoxide. Dibutyltin dimethoxide is the preferred initiator, and the course of polymerization is controlled by the competition of the ketone of OPD and the ester of the lactones for coordination to the initiator. Semicrystalline copolymers are formed, whose the randomness has been confirmed by DSC, H-1 NMR, and C-13 NMR analysis. A single melting temperature (Tm) has been observed, which varies regularly and monotonically with the OPD content as result of a cocrystallization phenomenom. The single glass transition temperature (Tg) obeys the Fox equation. [less ▲]

Detailed reference viewed: 41 (4 ULg)
Full Text
Peer Reviewed
See detailSelf-organization of water-soluble complexes of a poly(2-vinylpyridinium)-block-poly(ethylene oxide) diblock with fluorinated anionic surfactants
Gohy, Jean-François; Mores, Sandrine; Varshney, Sunil K et al

in Macromolecules (2003), 36(8), 2579-2581

Detailed reference viewed: 19 (2 ULg)
Full Text
Peer Reviewed
See detailAn energy transfer study of homopolymer localization in block copolymers
Rharbi, Yahya; Zhang, Jian-Xin; Spiro, John G et al

in Macromolecules (2003), 36(4), 1241-1252

We have investigated the localization of homopolystyrene (hPS) in its blends with poly(styrene-b-butyl methacrylate) (PS-b-PBMA), at 140 degreesC, measuring the quantum efficiency of direct energy ... [more ▼]

We have investigated the localization of homopolystyrene (hPS) in its blends with poly(styrene-b-butyl methacrylate) (PS-b-PBMA), at 140 degreesC, measuring the quantum efficiency of direct energy transfer (Phi(ET) of DET) between hPS randomly labeled with phenanthrene moieties and PS-b-PBMA labeled at the junction with anthracene. The molecular weight of hPS was similar to the molecular weight of the PS block of PS-b-PBMA, and the hPS content was kept to a maximum of 26 vol %, to preserve the lamellar morphology of PS-b-PBMA. We have found very low rates of DET, which implies that hPS is almost totally localized between the PS brushes of PS-b-PBMA. In addition to the experimental measurements, we also calculated Phi(ET) values by simulating fluorescence decay curves, based on Vavasour and Whitmore's numerical self-consistent-field (NSCF) formalism. The latter theory confirmed that we were dealing with a "dry brush" situation, but the NSCF results suggested a higher level of penetration of hPS than the experiments. We attribute this discrepancy to uncertainties about inputs to the simulations, particularly the Flory-Huggins chi parameter and the Kuhn length for the PBMA block. [less ▲]

Detailed reference viewed: 29 (0 ULg)
Full Text
Peer Reviewed
See detailProbing the stereoselectivity of the ruthenium-catalyzed ring-opening metathesis polymerization of norbornene and norbornadiene diesters
Delaude, Lionel ULg; Demonceau, Albert ULg; Noels, Alfred ULg

in Macromolecules (2003), 36(5), 1446-1456

The ring-opening metathesis polymerization (ROMP) of two optically active 2,3-dicarboalkoxynorbornadienes derived from (S)-(-)-2-methyl-1-butanol and (R)-(-)-2-butanol were carried out in the presence of ... [more ▼]

The ring-opening metathesis polymerization (ROMP) of two optically active 2,3-dicarboalkoxynorbornadienes derived from (S)-(-)-2-methyl-1-butanol and (R)-(-)-2-butanol were carried out in the presence of the [RuCl2(P-cymene)](2) catalyst precursor activated by trimethylsilyldiazomethane (TMSD). H-1 and C-13 NMR analyses showed that a high degree of stereoregularity was achieved, and homonuclear proton-proton COSY spectroscopy indicated that the major trans fractions of the polymers were most likely isotactic, while the minor cis fractions were syndiotactic. Ring-opened metathesis polymers were also made from 2,3-dicarbomethoxynorbornadiene and exo,exo-2,3-dicarbomethoxy-5-norbornene. They were hydrogenated into the corresponding polynorbornanes using diimide. The NMR spectra of the reduced materials confirmed that the unsaturated parent polymers had an all-trans highly isotactic microstructure. A tentative mechanism involving arene loss, carbene formation, and monomer chelation is proposed to account for the observed stereoselectivities. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailEffect of molecular weight of the reactive precursors in melt reactive blending
Yin, Zhihui; Koulic, Christian; Jeon, H. K. et al

in Macromolecules (2002), 35(24), 8917-8919

Detailed reference viewed: 10 (2 ULg)
Full Text
Peer Reviewed
See detailPoly(epsilon-caprolactone)/clay nanocomposites by in-situ intercalative polymerization catalyzed by dibutyltin dimethoxide
Lepoittevin, Bénédicte; Pantoustier, Nadège; Devalckenaere, Myriam et al

in Macromolecules (2002), 35(22), 8385-8390

Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-situ ring-opening polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na ... [more ▼]

Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-situ ring-opening polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+-montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. Exfoliated nanocomposites were formed when hydroxyl-containing alkylammonium. was used; otherwise, intercalated structures were reported. Thermogravimetric analyses showed a higher degradation temperature for the exfoliated structures than for the intercalated ones, both of them exceeding the degradation temperature of unfilled poly(epsilon-caprolactone). [less ▲]

Detailed reference viewed: 41 (5 ULg)
Full Text
Peer Reviewed
See detail2-oxepane-1,5-dione: A precursor of a novel class of versatile semicrystalline biodegradable (Co)polyesters
Latere, Jean-Pierre; Lecomte, Philippe ULg; Dubois, Philippe ULg et al

in Macromolecules (2002), 35(21), 7857-7859

Detailed reference viewed: 52 (9 ULg)
Full Text
Peer Reviewed
See detailControlled nitroxide-mediated radical polymerization of styrene, styrene/acrylonitrile mixtures, and dienes using a nitrone
Detrembleur, Christophe ULg; Sciannamea, Valérie; Koulic, Christian et al

in Macromolecules (2002), 35(19), 7214-7223

Radical polymerization of styrene and copolymerization of styrene and acrylonitrile (60/40) are controlled when conducted in the presence of N-tert-butyl-alpha-isopropylnitrone, which is easily ... [more ▼]

Radical polymerization of styrene and copolymerization of styrene and acrylonitrile (60/40) are controlled when conducted in the presence of N-tert-butyl-alpha-isopropylnitrone, which is easily synthesized from cheap reagents. However, for the control to be effective, the nitrone has to be prereacted with the radical initiator. Nitroxides are then formed "in situ", such that this nitrone system is an attractive alternative for the classical nitroxide-mediated polymerization (NMP), which may require a multistep synthesis of nitroxides or alkoxyamines. The choice of the radical initiator is important because it dictates the structure of the nitroxide and thus its capacity to control the radical polymerization. Well-defined poly(styrene)-b-poly(styrene-co-acrylonitrile), poly(styrene)-b-poly(n-butyl acrylate), and poly(styrene)-b-poly(isoprene) copolymers have been successfully synthesized by this process. [less ▲]

Detailed reference viewed: 51 (4 ULg)
Full Text
Peer Reviewed
See detailControlled ring-opening polymerization of epsilon-caprolactone in the presence of layered silicates and formation of nanocomposites
Kubies, Dana; Pantoustier, Nadège; Dubois, Philippe et al

in Macromolecules (2002), 35

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailControl of the radical polymerization of tert-butyl methacrylate in water by a novel combination of sodium nitrite and iron(II) sulfate
Detrembleur, Christophe ULg; Teyssié, Philippe; Jérôme, Robert ULg

in Macromolecules (2002), 35(5), 1611-1621

Addition of iron(II) sulfate to sodium nitrite is a new way to control the radical polymerization of tert-butyl methacrylate (tBMA) in water at 80 degreesC. Nitric oxide is released in the reaction medium ... [more ▼]

Addition of iron(II) sulfate to sodium nitrite is a new way to control the radical polymerization of tert-butyl methacrylate (tBMA) in water at 80 degreesC. Nitric oxide is released in the reaction medium as result of the reduction of sodium nitrite by FeSO4. This reaction is of utmost importance because three repeated additions of an alkyl radical to nitric oxide leads to the formation of nitroxide radicals. The basic mechanism for the control of the radical polymerization is thus a nitroxide-mediated process. [less ▲]

Detailed reference viewed: 28 (2 ULg)
Full Text
Peer Reviewed
See detailLiving cationic polymerization of delta-valerolactone and synthesis of high molecular weight homopolymer and asymmetric telechelic and block copolymer
Lou, Xudong; Detrembleur, Christophe ULg; Jérôme, Robert ULg

in Macromolecules (2002), 35(4), 1190-1195

Poly(delta-valerolactone) [poly(deltaVL)] of high molecular weight (similar to40 000) and low polydispersity index (similar to1.05) was prepared by activated monomer cationic ring-opening polymerization ... [more ▼]

Poly(delta-valerolactone) [poly(deltaVL)] of high molecular weight (similar to40 000) and low polydispersity index (similar to1.05) was prepared by activated monomer cationic ring-opening polymerization of delta-VL initiated by the alcohol/HCl.Et2O system. A series of functional alcohols, e.g., 9-anthracenemethanol, 2-hydroxyethyl acrylate, 3-buten-1-ol, 2-bromoethanol, and 5-norbornene-2-metbanol, were successfully used to prepare asymmetric telechelic poly(deltaVL), i.e., chains end-capped by the functional group of the alcohol in a-position and by an w-hydroxyl group. Ring-opening polymerization of delta-VL in the presence of alpha-methoxy-w-hydroxylpoly(ethylene oxide) and poly(ethylene glycol) led to amphiphilic di- and triblock copolymers, respectively. The polydispersity index of all these (co)polymers was low (similar to1.10). [less ▲]

Detailed reference viewed: 65 (1 ULg)
Full Text
Peer Reviewed
See detailpH-dependent micellization of poly(2-vinylpyridine)-block-poly((dimethylamino) ethyl methacrylate) diblock copolymers
Gohy, Jean-François; Antoun, Sayed; Jérôme, Robert ULg

in Macromolecules (2001), 34(21), 7435-7440

A series of poly(2-vinylpyridine)-block-poly((dimethylamino)ethyl methacrylate) diblock copolymers (P2VP-b-PDMAEMA) have been synthesized by living anionic polymerization of the comonomers. Dynamic light ... [more ▼]

A series of poly(2-vinylpyridine)-block-poly((dimethylamino)ethyl methacrylate) diblock copolymers (P2VP-b-PDMAEMA) have been synthesized by living anionic polymerization of the comonomers. Dynamic light scattering (DLS) has been used to study the associative behavior of these copolymers in water as a function of copolymer composition, pH, ionic strength, and temperature. Three association regimes are observed. At low pH, loose aggregates are formed, although both the P2VP and PDMAEMA blocks are protonated. At intermediate pH, micelles are observed that consist of an uncharged hydrophobic P2VP core surrounded by a protonated PDMAEMA corona. At higher pH, the PDMAEMA corona is essentially uncharged and collapses at temperatures higher than 40 °C, which results in unstable micelles. The micelles observed by transmission electron microscopy are spherical. [less ▲]

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailLiving ring-opening (co)polymerization of 6,7-dihydro-2(5H)-oxepinone into unsaturated aliphatic polyesters
Lou, Xudong; Detrembleur, Christophe ULg; Lecomte, Philippe ULg et al

in Macromolecules (2001), 34(17), 5806-5811

Homopolymerization of the unsaturated cyclic ester, 6,7-dihydro-2(5H)-oxepinone (DHO), and copolymerization with epsilon-caprolactone (epsilon-CL) are an easy way to produce unsaturated aliphatic ... [more ▼]

Homopolymerization of the unsaturated cyclic ester, 6,7-dihydro-2(5H)-oxepinone (DHO), and copolymerization with epsilon-caprolactone (epsilon-CL) are an easy way to produce unsaturated aliphatic polyesters in a controlled manner, Polymerization of DHO initiated by Al((OPr)-Pr-i)(3) in toluene at room temperature proceeds by a coordination-insertion mechanism and is living as certified by the agreement between the experimental molecular weight at total monomer conversion and the value predicted from the initial monomer to initiator molar ratio. The polydispersity is also low (Mw/Mn less than or equal to 1.2). Random copolymerization of DHO and epsilon-CL leads to the same conclusion. Beyond the complete monomer conversion, the poly(DHO) chains experience mainly intermolecular transesterification reactions at the same rate as poly(epsilon CL) under the same conditions. The livingness of the ROP of both DHO and epsilon-CL allows diblock copolymers to be synthesized with predicted composition and molecular weight. Homopoly(DHO) is semicrystalline with Tm at 35°C and Tg at -50°C. Tm and thermal stability can be modulated by copolymerization of DHO with epsilon-CL. [less ▲]

Detailed reference viewed: 18 (3 ULg)
Full Text
Peer Reviewed
See detailReactive blending of functional PS and PMMA: interfacial behavior of in situ formed graft copolymers
Yin, Zhihui; Koulic, Christian; Pagnoulle, Christophe et al

in Macromolecules (2001), 34(15), 5132-5139

ω-Isocyanate PMMA, α-anhydride PMMA, and PS-co-PSNH2 have been prepared by atom transfer radical polymerization (ATRP) with controlled molecular weights (104 and 3.5 × 104) and low polydispersity (1.2 ... [more ▼]

ω-Isocyanate PMMA, α-anhydride PMMA, and PS-co-PSNH2 have been prepared by atom transfer radical polymerization (ATRP) with controlled molecular weights (104 and 3.5 × 104) and low polydispersity (1.2). They have been used as precursors of PS-g-PMMA copolymers and let to react in the melt (170 °C, for 10 min) under moderate shear rate. The well-controlled molecular characteristics of these precursors are a substantial advantage to study the effect of the kinetics of the interfacial reaction on the phase morphology. When the grafting reaction is fast (NH2/anhydride pair) and low molecular weight chains are used, the interfacial reaction is quasi-complete and a nanophase morphology is observed, whereas limited reaction and formation of microphases are observed in all the other cases. A high reaction yield requires not only that the functional groups are highly mutually reactive but also that the interface is anytime made available to the functional polymers for the reaction to progress. Then, a nanophase morphology may be observed, which is that of the copolymer formed by the interfacial reaction. A low reaction yield is dictated by either a slow interfacial reaction or a slow diffusion of the copolymer away from the interface. In the latter case, the phases formed by the unreacted precursors are stabilized by the copolymer which resides at the interface. [less ▲]

Detailed reference viewed: 28 (1 ULg)
Full Text
Peer Reviewed
See detailProbing thermoplastic matrix-carbon fiber interphases. 1. Preferential segregation of low molar mass chains to the interface
Carlier, V.; Sclavons, M.; Jonas, Alain M et al

in Macromolecules (2001), 34(11), 3725-3729

The molecular mobility of polystyrene (PS) chains near the surface of carbon fibers was investigated. The glass transition temperature of very thin coatings deposited on carbon fibers was measured by ... [more ▼]

The molecular mobility of polystyrene (PS) chains near the surface of carbon fibers was investigated. The glass transition temperature of very thin coatings deposited on carbon fibers was measured by supported DMTA in order to probe the properties of the thermoplastic interphase. Depending on the fiber impregnation method from the melt or from solution, Tg changed in an opposite way for the thinnest coatings, decreasing with coating thickness in the case of impregnation in the melt and increasing when a polymer solution was used. This observation is explained by degradation of PS in the melt and subsequent preferential segregation of low molar mass chains to the interface. This conclusion is supported by the study of the Tg of coatings made from a bimodal molar mass distribution. [less ▲]

Detailed reference viewed: 24 (0 ULg)