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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 ▲]

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See detailModification of the polycarbonate/poly(vinylidene Fluoride) interface by poly(methyl methacrylate). Effect on the interfacial adhesion and interfacial tension
Moussaif, Noureddin; Jérôme, Robert ULg

in Macromolecular Symposia (1999), 139

Polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) are two immiscible polymers which form two-phase blends with weak interfacial adhesion and high interfacial tension This situation may be changed by ... [more ▼]

Polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) are two immiscible polymers which form two-phase blends with weak interfacial adhesion and high interfacial tension This situation may be changed by the addition of poly(methyl methacrylate) (PMMA), which concentrates preferably in the PVDF-rich phase, but also at the PVDF/PC interface. The interfacial activity of PMMA was estimated by the measurement of the interfacial adhesion and interfacial tension in relation to the PMMA content in the PVDF/PC blends. The interfacial adhesion between PC and homogeneous PVDF/PMMA blends of various compositions was measured by the dual cantilever beam technique The imbedded fiber retraction method was used for the measurement of the interfacial tension. A very beneficial effect was observed when PVDF was premixed with PMMA amounts increasing up to ca 35 wt-%., Beyond that content, the improvement tends to level off. [less ▲]

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See detailSynthesis of novel polymeric materials based on aliphatic polyesters by combination of different controlled polymerization methods
Jérôme, Robert ULg; Mecerreyes, David; Tian, Dong et al

in Macromolecular Symposia (1998), 132

Combination of the living ring-opening polymerization (ROP) of ε-CL and lactides with the "controlled" free radical polymerization of styrene and methacrylic monomers is a versatile strategy for the ... [more ▼]

Combination of the living ring-opening polymerization (ROP) of ε-CL and lactides with the "controlled" free radical polymerization of styrene and methacrylic monomers is a versatile strategy for the synthesis of well-defined block and graft copolymers. In this respect, the dual "living" polymerization strategy in which two different functional groups on a single molecule used to initiate the two controlled mechanisms is particularly efficient. Combination of ROP and step-growth polymerization is another versatile methodology for the preparation of a large variety of new materials, e.g. polyimide nanofbams, polyester/silica hybrid materials and star and branched polyesters by dendritic initiation. [less ▲]

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See detailLiving anionic polymerization of (meth)acrylic esters : new mechanistic concepts and resulting materials
Teyssié, Philippe; Baran, Janusz; Dubois, Philippe ULg et al

in Macromolecular Symposia (1998), 132

As an illustration of the frantic development of (meth)acrylic esters anionic polymerization during the last decade, three significant breakthroughs will be presented and analyzed: - extension of the LAP ... [more ▼]

As an illustration of the frantic development of (meth)acrylic esters anionic polymerization during the last decade, three significant breakthroughs will be presented and analyzed: - extension of the LAP (ligated anionic polymerization) concept to the practical synthesis of both high iso- or syndio high MW PMMA; - the production of "perfect" hydrocarbon gels from tailored PMMA-polybutadiene-PMMA triblock copolymers; - the use of reactivity "boosters" allowing to climb back up the nucleophilic reactivity scale, i.e. initiating styrene, dienes and (meth)acrylates polymerization with alcoholates and silanolates. [less ▲]

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See detailRing-opening polymerization of 1,4,8-trioxaspiro-[4.6]-9-undecanone: a route to novel molecular architectures for biodegradable aliphatic polyesters
Tian, Dong; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecular Symposia (1998), 130

The ring-opening polymerization of 1,4,8-trioxaspiro-[4,6]-9-undecanone (TOSUO) initiated by aluminum isopropoxide, Al(OiPr)3, is typically "living" and allows random and block copolyesters of predictable ... [more ▼]

The ring-opening polymerization of 1,4,8-trioxaspiro-[4,6]-9-undecanone (TOSUO) initiated by aluminum isopropoxide, Al(OiPr)3, is typically "living" and allows random and block copolyesters of predictable molecular weight and composition to be prepared. Deacetalization of the polyester chains is complete, and reduction of the accordingly formed ketone groups into hydroxyl groups as well. No chain scission is observed when these two derivatization reactions are carried out. The potential of these novel functional aliphatic polyesters has been discussed as drug colloidal vectors and macroinitiators for the synthesis of biodegradable and biocompatible comb, graft and even hyperbranched polymers. [less ▲]

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See detailBonding electropolymerization: a new electron-transfer strategy for the tailoring of performant polymer-based composites
Baute, Noëlle; Calberg, Cédric ULg; Dubois, Philippe ULg et al

in Macromolecular Symposia (1998), 134

Careful control of experimental conditions in the cathodic electropolymerization of acrylonitrile allows the grafting of thin polymer films, on conducting surfaces offering electrons easily mobilized at a ... [more ▼]

Careful control of experimental conditions in the cathodic electropolymerization of acrylonitrile allows the grafting of thin polymer films, on conducting surfaces offering electrons easily mobilized at a relatively low potential. Matching relative polarity and donicity of solvent and monomer expands the applicability of this methodology to the whole class of (meth)acrylic monomers, paving the way to many new and useful multiphase materials. [less ▲]

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See detailBulk polymerization of lactides initiated by aluminum isopropoxide. 1. Mechanism and kinetics
Degée, Philippe; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecular Symposia (1997), 123

Commercially available Al isopiopoxide (Al(OiPr)3) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring-opening polymerization proceeds through a "coordination ... [more ▼]

Commercially available Al isopiopoxide (Al(OiPr)3) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and the selective rupture of the acyl-oxygen bond of the monomer Polyester chains are selectively end-capped with an aluminum alkoxide and an isopropoxy group. Therefore, substitution of Al tris(4-penten-1-olate) for Al(OiPr)3 leads to the formation of macromonomers In the temperature range from 110 to 150°C, polymerization is "living", i.e. the molecular weight can be predicted by the initial monomer-to-Al molar ratio and the monomer conversion. The narrower polydispetsity of poly(L,L-lactide) compared to the amorphous poly(D,L-lactide) ( 1.3 compared to 1.9, respectively), both prepared in the bulk, is thought to result from the restricted mobility of the crystallized isotactic polyester chains. When the temperature is increased up to 180°C, inter- and intramolecular transesterification reactions interfere with chain propagation. [less ▲]

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See detailControl of living anionic polymerization of (meth)acrylates : active complex species, macromolecular engineering and possible scaling-up
Teyssié, Philippe; Bayard, Philippe; Jérôme, Robert ULg et al

in Macromolecular Symposia (1995), 98

Tailored polymerization of acrylic and methacrylic esters, particularly methyl methacrylate (MMA), has been the topic of a frantic research effort during the last decade. It is the purpose of this paper ... [more ▼]

Tailored polymerization of acrylic and methacrylic esters, particularly methyl methacrylate (MMA), has been the topic of a frantic research effort during the last decade. It is the purpose of this paper to present one of the main lines of that quest, and to evaluate its potential versus other new approaches. [less ▲]

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