References of "Macromolecular Symposia"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThermo-reversible reactions for the preparation of smart materials: recyclable covalently-crosslinked shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

in Macromolecular Symposia (2011), 309/310(1), 154-161

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the ... [more ▼]

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the nature of the Diels-Alder reactants, these bonds can be thermoreversibly broken, allowing re-processing of the polymer matrix. [less ▲]

Detailed reference viewed: 44 (17 ULg)
Full Text
Peer Reviewed
See detailNovel amphiphilic mikto-arm star-shaped copolymers for the preparation of PLA-based nanocarriers
Cajot, Sébastien ULg; Riva, Raphaël ULg; Billiet, Leen et al

in Macromolecular Symposia (2011), 309/310(1), 111-122

Three-arm (A2B) and four-arm (A2B2) star-shaped copolymers based on biocompatible and biodegradable hydrophobic poly(ε-caprolactone) (PCL) (A arms) and biocompatible and bioeliminable hydrophilic poly ... [more ▼]

Three-arm (A2B) and four-arm (A2B2) star-shaped copolymers based on biocompatible and biodegradable hydrophobic poly(ε-caprolactone) (PCL) (A arms) and biocompatible and bioeliminable hydrophilic poly(ethylene oxide) (PEO) (B arms) were synthesized by the coupling of an ω-azide terminated PEO chains with PCL chain bearing one (A2B) or two (A2B2) alkyne functions at the middle of the chain by the copper mediated azide-alkyne cycloaddition (CuAAC). The amphiphilic behavior of these different stars was confirmed by micellization experiments in water followed by dynamic light scattering and transmission electron microscopy analyses. The efficiency to stabilize PLA nanoparticles was investigated in function of the stars structure. [less ▲]

Detailed reference viewed: 54 (30 ULg)
Full Text
Peer Reviewed
See detailCharged poly(D,L-lactide) nanofibers: towards customized surface properties
Croisier, Florence ULg; Aqil, Abdelhafid ULg; Malherbe, Cédric ULg et al

in Macromolecular Symposia (2011), 309/310(1), 20-27

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP ... [more ▼]

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP process. In a basic medium, negative charges were therefore revealed on fiber surface. By deposition of positively charged particles or polyelectrolytes, surface properties of the fibers could be tailor-made for a specific application. This versatile method can, for example, be applied to the preparation of new biomedical scaffolds. [less ▲]

Detailed reference viewed: 43 (17 ULg)
Full Text
Peer Reviewed
See detailNew prospects for the grafting of functional groups onto aliphatic polyesters. Ring-opening polymerization of alpha- or gamma-substituted epsilon-caprolactone followed by chemical derivatization of the substituents
Lecomte, Philippe ULg; Riva, Raphaël ULg; Schmeits, Stephanie ULg et al

in Macromolecular Symposia (2006), 240

Recent progress in the synthesis of aliphatic polyesters, substituted by pendent functional groups, has been reviewed. Two main strategies have to be distinguished. The first route consists of the ring ... [more ▼]

Recent progress in the synthesis of aliphatic polyesters, substituted by pendent functional groups, has been reviewed. Two main strategies have to be distinguished. The first route consists of the ring-opening polymerization of F,caprolactone substituted by various functional groups, protected if needed, in alpha- or gamma-position. In a second strategy, the functional groups are grafted onto preformed polyesters chains in alpha-position of the carbonyl groups. alpha-chloro-epsilon-caprolactone is quite an interesting monomer because, after polymerization, the activated chloride can be easily derivatized by atom transfer radical addition and "click" chemistry, respectively. Similarly, gamma-acrylic-epsilon-caprolactone is precursor of (co)polyesters wellsuited to derivatization of the pendent double bonds by Michael addition. [less ▲]

Detailed reference viewed: 48 (11 ULg)
Full Text
Peer Reviewed
See detailPolymer layered silicate/carbon nanotube nanocomposites : Morphological and rheological properties
Peeterbroeck, Sophie; Alexandre, Michaël ULg; Nagy, Janos B et al

in Macromolecular Symposia (2005), 221

Morphological and rheological properties of new ternary nanocomposites based on ethylene vinyl acetate copolymers (EVA), commercial organo-modified clays (organoclays) and purified multi-walled carbon ... [more ▼]

Morphological and rheological properties of new ternary nanocomposites based on ethylene vinyl acetate copolymers (EVA), commercial organo-modified clays (organoclays) and purified multi-walled carbon nanotubes (MWNTs), prepared via direct melt blending, have been evaluated. For sake of comparison, the corresponding binary compositions, i.e., EVA filled with either organoclays or MWNTs, have been investigated as well. While extensive exfoliation can be observed for binary EVA/clay nanocomposites, the addition of MWNTs appears to limit clay exfoliation. Rheological properties show that both clay and MWNTs increase the elastic modulus of the nanocomposites, reflecting the high degree of nanoparticle interconnectivity that can be found in these materials. [less ▲]

Detailed reference viewed: 63 (5 ULg)
Full Text
Peer Reviewed
See detailContribution of supercritical CO2 to the preparation of aliphatic polyesters and materials thereof
Stassin, Fabrice; Jérôme, Robert ULg

in Macromolecular Symposia (2004), 217

This paper is a short review of the most recent achievments of CERM in the synthesis of poly (ε-caprolactone) (PCL) and polylactides (PLA) in supercritical carbon dioxide (sc CO2) In addition to the ... [more ▼]

This paper is a short review of the most recent achievments of CERM in the synthesis of poly (ε-caprolactone) (PCL) and polylactides (PLA) in supercritical carbon dioxide (sc CO2) In addition to the rrtacromolecular engineering of these aliphatic polyesters, nanocomposites and PCL microspheres have been prepared with the assistance of this supercritical fluid. [less ▲]

Detailed reference viewed: 14 (0 ULg)
Full Text
Peer Reviewed
See detailRecent developments in the ring-opening polymerization of epsilon-caprolactone and derivatives initiated by tin(IV) alkoxides
Lecomte, Philippe ULg; Stassin, Fabrice; Jérôme, Robert ULg

in Macromolecular Symposia (2004), 215

The macromolecular engineering of aliphatic polyesters by Ring-Opening Polymerization (ROP) initiated by aluminum alkoxides is now well established. Tin (IV) alkoxides are less popular, mainly because of ... [more ▼]

The macromolecular engineering of aliphatic polyesters by Ring-Opening Polymerization (ROP) initiated by aluminum alkoxides is now well established. Tin (IV) alkoxides are less popular, mainly because of a poorer control of the chain growth. This paper discusses some recent examples from CERM, showing that tin (IV) alkoxides can advantageously replace the aluminum counterparts as ROP initiators. For instance, they can initiate successfully the Ring-Opening Polymerization of α-chloro-ε-caprolactone and dioxepane-2-one. They are also very promising initiators for ROP in supercritical CO2 and for the synthesis of clay/aliphatic polyester nanocomposites. [less ▲]

Detailed reference viewed: 32 (9 ULg)
Full Text
Peer Reviewed
See detailDependence of the interfacial reaction and morphology development on the functionality of the reactive precursors in reactive blending
Yin, Zhihui; Koulic, Christian; Pagnoulle, Christophe et al

in Macromolecular Symposia (2003), 198

PMMA containing 50 wt% of anthracene-labeled PMMA chains end-capped by a phthalic anhydride group (anth-PMMA-anh) has been melt blended at 180°C with PS containing 33 wt% of chains end-capped by an ... [more ▼]

PMMA containing 50 wt% of anthracene-labeled PMMA chains end-capped by a phthalic anhydride group (anth-PMMA-anh) has been melt blended at 180°C with PS containing 33 wt% of chains end-capped by an aliphatic primary amine (PS-NH2) and PS bearing 3.5 pendant amine groups (as an average) along the chains (PS-co-PSNBH2), respectively. The reactive chains have been synthesized by atom transfer radical polymerization. Conversion of anth-PMMA-anh into PS-b-PMMA and PS-g-PMMA copolymers has been monitored by SEC with a UV detector. The interfacial reaction mainly occurs in the initial melting and softening stage (<1.0 mm), although at a rate which strongly depends on the number of reactive groups attached to PS chains, the higher conversion being observed for the PS-co-PSNH2 containing blends. The phase morphology depends on the architecture of the in-situ formed copolymer Indeed, a coarser phase dispersion is observed in case of the graft copolymer compared to the diblock. [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailReactively and physically compatibilized immiscible polymer blends: Stability of the copolymer at the interface
Harrats, Charef; Dedecker, Kristof; Groeninckx, Gabriel et al

in Macromolecular Symposia (2003), 198

This paper reports on the interfacial behaviour' of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been ... [more ▼]

This paper reports on the interfacial behaviour' of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/ PA6 and polymethylmethaciylate (PMMA)/PA6 blends have . been reactively compatibilized by a styrene-maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer' at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence. In PS/LDPE blends compatibilized by preformed PS / hydrogenated polybutadiene (hPB) block copolymers, a tapered diblock stabilizes efficiently a co-continuous two-phase morphology, in contrast to a triblock copolymer that was unable to prevent phase coarsening during annealing at 180°C for 150 minutes. [less ▲]

Detailed reference viewed: 33 (1 ULg)
Full Text
Peer Reviewed
See detailPolymerization-filled composites and nanocomposites by coordination catalysis
Dubois, Philippe ULg; Alexandre, Michaël ULg; Jérôme, Robert ULg

in Macromolecular Symposia (2003), 194

Polyolefinic microcomposites and layered silicate nanocomposites were prepared by the in-situ polymerization of ethylene (and alpha-olefin) via the so-called polymerization-filling technique. Various ... [more ▼]

Polyolefinic microcomposites and layered silicate nanocomposites were prepared by the in-situ polymerization of ethylene (and alpha-olefin) via the so-called polymerization-filling technique. Various tillers with either basic, acidic, metallic or carbonaceous surface, as well as non-modified clays such as montmorillonite and hectorite, were first treated by trimethylaluminum-depleted methylaluminoxane before being contacted by a titanium or zirconium-based metallocene catalyst. The (nano)composite was formed by addition and polymerization of ethylene (and alpha-olefin). This technique makes possible the complete encapsulation of every filler particle within the (co)polyolefinic matrix ranging from thermoplastics to elastomers. The so-obtained (nano)composites, often coined as "homogeneous" (nano)composites, exhibit improved mechanical properties; as compared to more conventional melt blends for a same filler content. [less ▲]

Detailed reference viewed: 49 (0 ULg)
Full Text
Peer Reviewed
See detailLayered silicate/polyester nanohybrids by controlled ring-opening polymerization
Lepoittevin, Bénédicte; Pantoustier, Nadège; Alexandre, Michaël ULg et al

in Macromolecular Symposia (2002), 183

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These ... [more ▼]

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These nanocomposites were formed in presence of montmorillortite surface-modified by ammonium cations bearing hydroxyl group(s), such as bis(2-hydroxyethyl)methyl (hydrogenated tallow alkyl) ammonium. The lactone polymerization could in initiated by all the hydroxyl functions available at the clay surface, after activation into either tin(II) or AI(III) alkoxide active species. Hybrid nanocomposites were accordingly generated through the covalent grafting of every polyester chain onto the filler surface. Surface-grafted polycaprolactone (PCL) chains were untied and isolated by ionic exchange reaction with LiCl in THF solution and molar masses were measured by size exclusion chromatography. The PCL molar masses could be controlled and readily tuned by the content of hydroxyl groups available at the clay surface. Interestingly, initiation reaction by aluminum trialkoxide active species yielded grafted PCL chains characterized by very narrow molecular weight distribution (M-w/M(n)similar to1.2). These polyester-grafted layered silicate nanohybrids displayed complete exfoliation of silicate sheets as shown by X-ray diffraction (XRD) and transmission electron microscopy (TEM). [less ▲]

Detailed reference viewed: 19 (0 ULg)
Full Text
Peer Reviewed
See detailContribution of unsymmetrical difunctional initiators/monomers to the macromolecular engineering
Jérôme, Robert ULg

in Macromolecular Symposia (2002), 177

The emerging technologies (e.g. in optics, microelectronics, medicine...) require the availability of synthetic polymers with continuously more sophisticated properties and performances. The best way for ... [more ▼]

The emerging technologies (e.g. in optics, microelectronics, medicine...) require the availability of synthetic polymers with continuously more sophisticated properties and performances. The best way for the polymer chemist to face this challenge is to tailor the molecular structure of the chains. Nowadays, the progress in the living/controlled polymerization mechanisms is such that the so-called macromolecular engineering is a vivid reality. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailPhase-separated microstructures in "all-acrylic" thermoplastic elastomers
Leclère, Philippe; Rasmont, A.; Brédas, Jean-Luc et al

in Macromolecular Symposia (2001), 167

Atomic Force Microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. Measuring simultaneously the amplitude and the phase of the oscillating ... [more ▼]

Atomic Force Microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. Measuring simultaneously the amplitude and the phase of the oscillating cantilever in tapping-mode operation provides the surface topography along with the cartography of microdomains with different mechanical properties. This in turn allows to characterize the organization of the various components at the surface in terms of well-defined morphologies (e.g., spheres, cylinders, or lamellae). Here this approach is applied to a series of symmetric triblock copolymers made of a central elastomeric segment (polyalkylacrylate) surrounded by two thermoplastic sequences (polymethylmethacrylate). The occurrence of microphase separation in these materials and the resulting microscopic morphology are essential factors for determining their potential applications as a new class of thermoplastic elastomers. This paper describes how the surface morphology can be controlled by the molecular structure of the copolymers (volume ratio between the sequences, molecular weight, length of the alkyl side group) and by the experimental conditions used for the preparation of the films. The molecular structure of the chains is fully determined by the synthesis of the copolymers via living anionic polymerization while the parameters that can be modified when preparing the samples are the nature of the solvent and the thermal annealing of the films. Finally, we report on a systematic comparison between images and approach-retract curve data. We show that this experimental comparison allows the origin of the contrast that produces the image to be straightforwardly evaluated. The method provides an unambiguous quantitative measurement of the contribution of the local mechanical response to the image. We show that most of the contrast in the height and phase images is due to variations in local mechanical properties and not in topography. [less ▲]

Detailed reference viewed: 57 (0 ULg)
Full Text
Peer Reviewed
See detailSynthesis of new (pyrrole-g- ε-caprolactone) copolymers
Jérôme, Christine ULg; Martinot, Lucien; Louette, Pierre et al

in Macromolecular Symposia (2000), 153

Poly-ε-caprolactone end-capped by a pyrrole moiety has been synthesized and successfully copolymerized with pyrrole with formation of new brush copolymers. Copolymerization has been achieved by ... [more ▼]

Poly-ε-caprolactone end-capped by a pyrrole moiety has been synthesized and successfully copolymerized with pyrrole with formation of new brush copolymers. Copolymerization has been achieved by electrochemical and chemical techniques. Formation of copolymer has been confirmed by various methods including XPS, DSC, TGA, and SEM. The effect of the PCL branches on conductivity, morphology and stability of PPy has been studied. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
Peer Reviewed
See detailRing opening copolymerization of ε-caprolactone, γ-(triethylsilyloxy)-ε-caprolactone and γ-ethylene ketal-ε-caprolactonelactone: a route to hetero-graft copolyesters
Stassin, Fabrice; Halleux, Olivier; Dubois, Philippe ULg et al

in Macromolecular Symposia (2000), 153

ε-Caprolactone (ε-CL) has been copolymerized with two precursors of γ-hydroxy-ε-CL, i.e., γ-ethylene ketal-ε-caprolactone (TOSUO) and γ-(triethylsilyloxy)-ε-caprolactone (TeSCL). The triethylsilyloxy ... [more ▼]

ε-Caprolactone (ε-CL) has been copolymerized with two precursors of γ-hydroxy-ε-CL, i.e., γ-ethylene ketal-ε-caprolactone (TOSUO) and γ-(triethylsilyloxy)-ε-caprolactone (TeSCL). The triethylsilyloxy pendant groups can be selectively deprotected into hydroxyl groups followed by the deprotection of the acetal substituents. Each series of hydroxyl groups can be used to initiate the polymerization of cyclic monomers so leading to hetero-graft copolyesters with, for instance, poly-ε-CL and polylactide grafts. [less ▲]

Detailed reference viewed: 37 (4 ULg)
Full Text
Peer Reviewed
See detailContinuous reactive extrusion polymerization of L-lactide - an engineering view
Jacobsen, Sven; Fritz, Hans-Gerhard; Degée, Philippe et al

in Macromolecular Symposia (2000), 153

Polylactides (PLA), biodegradable aliphatic polyesters, produced from renewable resources might substitute petrochemically based polymers in a broad range of applications in the near future, if we manage ... [more ▼]

Polylactides (PLA), biodegradable aliphatic polyesters, produced from renewable resources might substitute petrochemically based polymers in a broad range of applications in the near future, if we manage to produce them at lower cost and higher efficiency than nowadays. Possible applications include food packaging for meat and soft drinks, films for agro-industry and non-wovens in hygienic products. The authors developed, based on a new catalytic system, a reactive extrusion polymerisation process, which can be used to produce PLA continuously in larger quantities and at lower costs than before. This extrusion polymerisation process has been developed and tested with laboratory scale machines and has to be transferred to industrial processing equipment. This paper aims to address the problems attached with this transfer and to discuss the chances to finally achieve low cost PLA at industrial scale. [less ▲]

Detailed reference viewed: 113 (3 ULg)
Full Text
Peer Reviewed
See detailReactive compatibilization of SAN/EPR blends: Effect of kinetics of the compatibilization reaction on the interfacial adhesion
Pagnoulle, Christophe; Jérôme, Robert ULg

in Macromolecular Symposia (2000), 149

The very poor adhesion between films of styrene and acrylonitrile random copolymer (SAN) and maleic anhydride grafted polypropylene (PP-g-MA) can be dramatically improved by an intermediate thin layer of ... [more ▼]

The very poor adhesion between films of styrene and acrylonitrile random copolymer (SAN) and maleic anhydride grafted polypropylene (PP-g-MA) can be dramatically improved by an intermediate thin layer of SAN bearing groups reactive toward maleic anhydride. The rate of the interfacial reaction, which is controlled by the reactive groups attached to SAN (amine vs. carbamate) and by the method used to build up the sandwich assembly, has a decisive effect on the capability of the SAN-g-PP graft copolymer formed at the interface to improve the fracture toughness in direct dependence on its molecular architecture. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
Peer Reviewed
See detailRuthenium-based catalysts for the ring-opening metathesis polymerization (ROMP) of functionalized cyclic olefins
Delaude, Lionel ULg; Jan, Dominique; Simal, François et al

in Macromolecular Symposia (2000), 153

Recent developments in Ring-Opening Metathesis Polymerization (and copolymerization) of functionalized cycloolefins with well-defined ruthenium-based initiators are summarized and illustrated with ... [more ▼]

Recent developments in Ring-Opening Metathesis Polymerization (and copolymerization) of functionalized cycloolefins with well-defined ruthenium-based initiators are summarized and illustrated with synthesis of graft copolymers, telechelic and liquid crystalline polymers, glycopolymers and unsaturated ester-functionalized oligomers. [less ▲]

Detailed reference viewed: 19 (1 ULg)
Full Text
Peer Reviewed
See detailNovel functionalization routes of poly(ε-caprolactone)
Lecomte, Philippe ULg; Detrembleur, Christophe ULg; Lou, Xudong et al

in Macromolecular Symposia (2000), 157

The aluminum alkoxide mediated ring opening polymerization of functional lactones, such as γ-ethylene ketal-ε-caprolactone (TOSUO), γ-(triethylsilyloxy)-ε-caprolactone (SCL) and γ-bromo-ε-caprolactone ... [more ▼]

The aluminum alkoxide mediated ring opening polymerization of functional lactones, such as γ-ethylene ketal-ε-caprolactone (TOSUO), γ-(triethylsilyloxy)-ε-caprolactone (SCL) and γ-bromo-ε-caprolactone (γBrCL), is a versatile route to polyesters containing ketal, ketone, alcohol and bromide groups. As result of living polyaddition mechanism, random and block copolymerization of εCL and γBrCL has been successfully carried out. The reactivity ratios are quite similar (1.08 for ε-CL, and 1.12 for γBrCL). These random copolymers are semicrystalline when they contain less than 30 mol% of γBrCL, otherwise they are amorphous. No transesterification reaction occurs during the sequential polymerization of ε-CL and γBrCL leading to block copolymers. Reaction of poly(εCL-co-γBrCL) with pyridine provides quantitatively a polycationic polyester. Furthermore, the reaction of this random copolymer with l,8-diazabicyclo[5.4.0] undec-7-ene (DBU) is a route to unsaturated polyesters, whose the non conjugated double bonds can be quantitatively converted into epoxides by reaction with m-chloroperbenzoic acid (mCPBA). No chain degradation is detected during these derivatization reactions of poly (εCL-co-γBrCL). [less ▲]

Detailed reference viewed: 56 (10 ULg)
Full Text
Peer Reviewed
See detailNew catalysis for fast bulk ring-opening polymerization of lactide monomers
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecular Symposia (1999), 144

The ring-opening polymerization of lactides has been studied in bulk using either 2-ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of ... [more ▼]

The ring-opening polymerization of lactides has been studied in bulk using either 2-ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of temperature and monomer-to-initiator molar ratio, A high increase in the bulk polymerization rate has been observed when the initiator was added with an equimolar amount of a Lewis base, such as triphenylphosphine and 4-picoline (C6H7N) added to Sn(Oct)2 and Al(OiPr)3, respectively Melt stable polylactides of high molecular weight and reasonably narrow molecular weight distribution have been accordingly prepared. The use of the Sn(Oct)2. equimolar combination has allowed for reaching an acceptable balance between propagation and depolymerization rates, so that the polymerization is fast enough to be performed through a continuous single-stage process in a twin-screw extruder A global activation mechanism is proposed and discussed by comparison with both investigated initiation systems. [less ▲]

Detailed reference viewed: 81 (12 ULg)