References of "Riva, Raphaël"
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See detailContribution of "click chemistry" to the synthesis of antimicrobial aliphatic copolyester
Riva, Raphaël ULg; Lussis, Perrine ULg; Lenoir, Sandrine ULg et al

in Polymer (2008), 49(8), 2023-2028

A straightforward strategy is proposed to impart antimicrobial properties to biodegradable poly(oxepan-2-one) (poly(epsilon-caprolactone) or PCL), which is based on the grafting of pendant ammonium salts ... [more ▼]

A straightforward strategy is proposed to impart antimicrobial properties to biodegradable poly(oxepan-2-one) (poly(epsilon-caprolactone) or PCL), which is based on the grafting of pendant ammonium salts by "click" chemistry. First, statistical copolymerization of 3-chlorooxepan-2-one (alpha-chloro-epsilon-caprolactone or alpha Cl epsilon CL) with oxepan-2-one (epsilon-caprolactone or epsilon CL) was initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP). In a second step, pendant chlorides were converted into azides by reaction with sodium azide (NaN3). Finally, quaternary ammonium containing alkynes were quantitatively added to the pendant azide groups of PCL by the copper-catalyzed Huisgen's 1,3-dipolar cycloaddition, which is a typical "click" reaction. An alternative two-step strategy based on the cycloaddition of the amine containing alkyne onto the pendant azides, followed by quaternization turned out to be less efficient. The antimicrobial activity was analyzed by the "shaking flask method" in the presence of Escherichia coli [less ▲]

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See detailSynthesis of novel functional aliphatic polyesters by association of ring-opening polymerization and click chemistry
Lecomte, Philippe ULg; Schmeits, Stephanie ULg; Riva, Raphaël ULg et al

Conference (2008, April 09)

Nowadays, biodegradable and biocompatible aliphatic polyesters are widely used as environmentally friendly thermoplastics and biomaterials. Nevertheless, the absence of any functional group along the ... [more ▼]

Nowadays, biodegradable and biocompatible aliphatic polyesters are widely used as environmentally friendly thermoplastics and biomaterials. Nevertheless, the absence of any functional group along the chain is a severe limitation for the development of new applications. Very recently, it was reported by Emrick et al. and by us that copper(I)-mediated 1,3-dipolar Huisgen's cycloaddition of alkynes and azides, the most widely used “click” reaction in the frame of macromolecular engineering, is very efficient to derivatize aliphatic polyesters. Due to the tolerance for many functional groups, cumbersome protection and deprotection steps are not needed. One main advantage of copper(I)-mediated Huisgen's cycloaddition compared to other reactions previously used to derivatize aliphatic polyesters relies on the mildness of the experimental conditions, which results in limited degradation. Our most recent results dealing with the combination of “click” chemistry and ring-opening polymerization towards functional PCL and PLA, networks, graft and hyperbranched copolymers will be highlighted. [less ▲]

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See detailPH-responsive biodegradable amphiphilic networks
Zednik, Jiri; Riva, Raphaël ULg; Lussis, Perrine ULg et al

in Polymer (2008), 49(3), 697-702

Copper-mediated azide - alkyne Huisgen's 1,3-dipolar cycloaddition is a "click" reaction that was successfully used to prepare pH-responsive, amphiphilic and biodegradable networks. Indeed, this reaction ... [more ▼]

Copper-mediated azide - alkyne Huisgen's 1,3-dipolar cycloaddition is a "click" reaction that was successfully used to prepare pH-responsive, amphiphilic and biodegradable networks. Indeed, this reaction proved to be very efficient in the "one pot" grafting of amino alkyne onto azide containing poly(epsilon-caprolactone) and the cross-linking of these chains by alpha,omega-dialkynyl poly(ethylene oxide). The pH-controlled release of guests hosted during the cross-linking step was illustrated with an entrapped model dye. [less ▲]

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See detailSynthesis of eight-shaped and star-shaped poly(ε-caprolactone) and their amphiphilic derivatives
Li, Haiying; Riva, Raphaël ULg; Kricheldorf, Hans R. et al

in Chemistry : A European Journal (2008), 14(1), 358-368

Spirocyclic tin dialkoxides are unique initiators for the ring-expansion polymerization of lactones leading to complex, but well-defined macromolecular architectures. In a first example, -caprolactone (CL ... [more ▼]

Spirocyclic tin dialkoxides are unique initiators for the ring-expansion polymerization of lactones leading to complex, but well-defined macromolecular architectures. In a first example, -caprolactone (CL) was polymerized, followed by the resumption of polymerization of a mixture of CL and CL -substituted by a chloride (ClCL), so leading to living eight-shaped chains. Upon hydrolysis of the alkoxides, a four-arm star-shaped copolyester was formed, whose each arm was grafted by conversion of the chloride units into azides, followed by the Huisgen's [3+2] cycloaddition of alkyne end-capped poly(ethylene oxide) (PEO) onto the azide substituents. The complexity of this novel amphiphilic architecture was increased further by substituting the four-arm interconnecting PCL by an eight-shaped PCL. In a preliminary step, CL was polymerized followed by a few units of CL -substituted by an acrylate. The intramolecular photo-crosslinking of the acrylates adjacent to the tin dialkoxides was effective in stabilizing the eight-shaped polyester while preserving the chain growth sites. This quite unusual tetrafunctional macroinitiator was used to copolymerize CL and ClCL, followed by hydrolysis of the alkoxides, conversion of the chloride units into azides and grafting of the four arms by PEO (see above). This architecture reported for the very first time is nothing but a symmetrical four-tail eight-shaped copolyester macromolecule. [less ▲]

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See detailSynthesis of novel functional aliphatic polyesters
Schmeits, Stephanie ULg; Riva, Raphaël ULg; Jérôme, Christine ULg et al

in Polymer Preprints (2008), 49(1), 222-223

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See detailDEVELOPMENT OF AN INTRAPERITONEAL IMPLANT FOR THE ENDOMETRIOSIS TREATMENT
Krier, Fabrice ULg; Nizet, Dominique; Riva, Raphaël ULg et al

Poster (2008)

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See detailMacromolecular engineering of cyclic aliphatic polyesters by ring-opening polymerization and "click" chemistry
Lecomte, Philippe ULg; Li, Haiying; Riva, Raphaël ULg et al

Conference (2007, September 04)

The last decades have witnessed a steadily increasing progress in the macromolecular engineering of the main families of synthetic polymers. Ring-shaped copolymers show a unique topology due to the ... [more ▼]

The last decades have witnessed a steadily increasing progress in the macromolecular engineering of the main families of synthetic polymers. Ring-shaped copolymers show a unique topology due to the absence of any chain-end and exhibit distinct properties from their linear counterparts, such as glass transition temperature, order-disorder transition, reduced viscosity, lower hydrodynamic volumes. This communication aims at reporting on a novel route to biodegradable cyclic polyesters. Our strategy is based on the work of Prof. Kricheldorf who initiated the ring-opening polymerization of ε-caprolactone by cyclic tin dialkoxides, e.g., 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) in order to obtain “living” macrocyclic PCL, still containing two endocyclic tin-oxygen bonds. In this work, the resumption of polymerization by a few units of ε-caprolactone substituted by an acrylic unit, e.g., 1-(2-oxooxepan-3-yl)ethyl prop- 2-enoate, followed by intramolecular photo-crosslinking of pendant unsaturations and finally by hydrolysis gave rise to macrocyclic PCL. As a rule, this strategy is very well-suited for the synthesis of high molecular weight PCL. Moreover, tin alkoxides were kept untouched after the cross-linking step and remained thus available for further macromolecular engineering. The process was extended to the synthesis of other architectures such as sun-shaped, two-tail tadpoleshaped, and eight-shaped copolyesters. The second part of the lecture, it will be shown that the copper(I)-catalyzed Huisgen’s [3+2] cycloaddition, which is the most popular “Click" reaction, is very efficient to graft alkynes, duly substituted by functional groups or chains, onto aliphatic copolyesters bearing pendant azides. Interestingly enough, mild conditions were found and no degradation was observed during the “click” derivatization of copolyesters of PCL. The “click” reactions of alkynes onto pendant azides of copolyesters of PLA, by far more sensitive than PCL, was also successfully carried out without any detectable degradation. ”Click” chemistry is very versatile because this reaction was successfully implemented to graft functional groups or chains directly onto ω-azido-ε-caprolactone, without any ring-opening of the lactone, in order to make available a new range of functional caprolactones. Finally, the “click” grafting of PEO onto the tails of tadpole-shaped copolymers will be shown to be a route to amphiphilic copolymers with an original architecture. [less ▲]

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See detailContribution of "click" chemistry to the functionalization of aliphatic polyesters
Schmeits, Stephanie ULg; Riva, Raphaël ULg; Zednik, Jiri et al

Poster (2007, August 31)

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See detailMacromolecular engineering of aliphatic polyesters based on macrocyclic units
Lecomte, Philippe ULg; Li, Haiying; Riva, Raphaël ULg et al

Poster (2007, August 31)

The last decades have witnessed a steadily increasing progress in the macromolecular engineering of the main families of synthetic polymers. Ring-shaped copolymers show a unique topology due to the ... [more ▼]

The last decades have witnessed a steadily increasing progress in the macromolecular engineering of the main families of synthetic polymers. Ring-shaped copolymers show a unique topology due to the absence of any chain-end and exhibit distinct properties from their linear counterparts, such as glass transition temperature, order-disorder transition, reduced viscosity, lower hydrodynamic volumes. This communication aims at reporting on a novel route to biodegradable cyclic polyesters. Our strategy is based on the work of Prof. Kricheldorf who initiated the ring-opening polymerization of ε-caprolactone by cyclic tin dialkoxides, e.g., 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) in order to obtain “living” macrocyclic PCL, still containing two endocyclic tin-oxygen bonds. In this work, the resumption of polymerization by a few units of ε-caprolactone substituted by an acrylic unit, e.g., 1-(2-oxooxepan-3-yl)ethyl prop-2-enoate, followed by intramolecular photo-cross-linking of pendant unsaturations and finally by hydrolysis gave rise to macrocyclic PCL. As a rule, this strategy is very well-suited for the synthesis of high molecular weight PCL. Moreover, tin alkoxides were kept untouched after the cross-linking step and remained thus available for further macromolecular engineering. The process was extended to the synthesis of other architectures such as sun-shaped, two-tail tadpole-shaped, eight-shaped and symmetrical four-tail eight-shaped copolyesters. [less ▲]

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See detailMacromolecular engineering of poly(ε-caprolactone) based on macrocyclic units
Lecomte, Philippe ULg; Li, Haiying; Riva, Raphaël ULg et al

Poster (2007, May 24)

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See detailFunctionalization of poly(ε-caprolactone) and its macromolecular engineering
Riva, Raphaël ULg

Doctoral thesis (2007)

Macromolecular engineering is one of the most powerful tools to control the molecular parameters, including architecture of polymers, and to improve their performances or to impart them new properties ... [more ▼]

Macromolecular engineering is one of the most powerful tools to control the molecular parameters, including architecture of polymers, and to improve their performances or to impart them new properties. This contribution aims at reporting on a novel strategy for the macromolecular engineering of poly-ε-caprolactone (PCL) which is based on the use of functional ε-caprolactone, the α-chloro-ε-caprolactone (αClεCL). Indeed, αClεCL is a precursor of polymers and copolymers with εCL that bear pendant activated chlorides well suited to “grafting from” reaction. These (co)polyesters have been used as macroinitiators for the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate leading to the corresponding graft copolymer. They have also been involved in an Atom Transfer Radical Addition (ATRA) reaction with a series of olefins bearing different functional groups (hydroxyl, carboxylic acid and epoxy group) in order to functionalize the polyester backbone without deleterious degradation. ATRA of PEO chains with an unsaturation end groups has also been carried out in order to prepare PCL-g-PEO of different compositions to be used as stabilizers of polyester nanoparticles. Combination of ring-opening polymerization of ε-caprolactone and the copper-catalyzed Huisgen’s [3+2] cycloaddition is a novel strategy for going a step further in the macromolecular engineering of poly-ε-caprolactone (PCL). This ‘click” reaction is very well-suited to the chemical modification of aliphatic polyesters because, its implementation under very mild conditions prevents chain degradation from occurring. Indeed, alkynes were cycloadded onto azide containing PCL at low temperature (35°C) in an organic solvent (DMF or THF). Originally, α-chloro-ε-caprolactone and ε-caprolactone were randomly copolymerized in toluene at room temperature followed by reaction of the activated chlorides with sodium azide. In order to make a wide range of functional aliphatic polyesters available, poly(α-azide-ε-caprolactone-co-ε-caprolactone) copolyesters were reacted with a series of alkynes substituted by a functional group, e.g., hydroxyl, acrylate and quaternary ammonium salts, This strategy turned out to be efficient to synthesize for instance hydrophilic, photo-cross-linkable and hydrosoluble PCL. Moreover, a variety of graft copolymers were prepared by both the “grafting from” and the “grafting onto” techniques. Indeed, an ATRP initiator was attached onto PCL followed by polymerization of vinyl monomers, whereas alkyne end–capped PEO was cycloadded onto azide-containing PCL with formation of amphiphilic PCL-g-PEO copolymers. Last but not least, the “click” chemistry was very instrumental in imparting an antimicrobial activity to PCL or for the preparation of new functionalized caprolactones. [less ▲]

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See detailSynthesis of new substituted lactones by "click" chemistry
Riva, Raphaël ULg; Chafaqi, Laila; Jérôme, Robert ULg et al

in Arkivoc (2007), (x), 292-306

Several new oxepan-2-ones substituted by an ester, an ammonium, a hydroxyl, an acrylate and a poly(ethylene oxide) chain, respectively, were synthesized by the Huisgen's [3+2] cycloaddition of duly ... [more ▼]

Several new oxepan-2-ones substituted by an ester, an ammonium, a hydroxyl, an acrylate and a poly(ethylene oxide) chain, respectively, were synthesized by the Huisgen's [3+2] cycloaddition of duly substituted alkynes onto 5-azidooxepan-2-one. [less ▲]

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See detailCombination of ring-opening polymerization and "click chemistry": Toward functionalization and grafting of poly(epsilon-caprolactone)
Riva, Raphaël ULg; Schmeits, Stéphanie; Jérôme, Christine ULg et al

in Macromolecules (2007), 40(4), 796-803

A straightforward strategy is proposed for the derivatization of poly(epsilon-caprolactone) (PCL). First, statistical copolymerization of alpha-chloro-epsilon-caprolactone (alpha-Cl-epsilon-CL) with ... [more ▼]

A straightforward strategy is proposed for the derivatization of poly(epsilon-caprolactone) (PCL). First, statistical copolymerization of alpha-chloro-epsilon-caprolactone (alpha-Cl-epsilon-CL) with epsilon-caprolactone (epsilon-CL) was initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP). In a second step, pendent chlorides were converted into azides by reaction with sodium azide. Finally, duly substituted terminal alkynes were reacted with pendent azides by copper-catalyzed Huisgen's 1,3-dipolar cycloaddition, thus a "click" reaction. According to this strategy, pendent hydroxyl and acrylate groups and atom transfer radical polymerization (ATRP) initiators were successfully attached to PCL. Similarly, amphiphilic graft copolymers were prepared by cycloaddition of an alkyne end-capped poly(ethylene oxide) (PEO) onto the azide substituents of the copolyester. The dependence of the grafting yield on the experimental conditions of the "click" reaction, i.e., temperature, solvent, and catalyst, was investigated. This strategy is very versatile because a large variety of aliphatic polyesters can be easily synthesized from a single precursor, easily prepared from commercially available compounds, merely by changing the alkyne involved in the Huisgen's 1,3-dipolar cycloaddition. Last but not least, PCL subsituted by azide groups does not have to be isolated after substitution of chlorides by sodium azide, and the "click" reaction can be carried out in a "one-pot" process. [less ▲]

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See detailCombination of ring-opening polymerization and "click" chemistry for the synthesis of an amphiphilic tadpole-shaped poly(epsilon-caprolactone) grafted by PEO
Li, Haiying; Riva, Raphaël ULg; Jérôme, Robert ULg et al

in Macromolecules (2007), 40(4), 824-831

A tadpole shaped poly(epsilon-caprolactone) (PCL; Mn = 24 500) was made amphiphilic by grafting the two PCL tails with PEO. In the first step, a macrocyclic PCL was synthesized by ring-opening ... [more ▼]

A tadpole shaped poly(epsilon-caprolactone) (PCL; Mn = 24 500) was made amphiphilic by grafting the two PCL tails with PEO. In the first step, a macrocyclic PCL was synthesized by ring-opening polymerization of epsilon-caprolactone (epsilon-CL) initiated by a cyclic tin(IV) dialkoxide and stabilized by local intramolecular photo-cross-linking. In the second step, the polymerization of a mixture of epsilon CL and alpha-chloro-epsilon-caprolactone (alpha Cl epsilon CL) was resumed with formation of two activated chloride containing PCL tails. In the third step, the chlorides were converted into azides onto which alkynyl end-capped PEO was grafted by the copper-mediated Huisgen's cycloaddition [3 + 2], thus giving a "click" reaction. The thermal properties of the final copolymer and the precursors were analyzed by differential scanning calorimetry. The amphiphilicity of the final copolymer was confirmed by micellization in water. [less ▲]

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See detailDEVELOPMENT OF AN INTRAPERITONEAL IMPLANT FOR THE ENDOMETRIOSIS TREATMENT
Krier, Fabrice ULg; Nizet, Dominique; Riva, Raphaël ULg et al

Conference (2007)

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See detailHeterograft copolymers of poly(epsilon-caprolactone) prepared by combination of ATRA "grafting onto" and ATRP "grafting from" processes
Riva, Raphaël ULg; Rieger, Jutta ULg; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2006), 44(20), 6015-6024

This paper aims at reporting on the synthesis of a heterograft copolymer by combining the "grafting onto" process based on atom transfer radical addition (ATRA) and the "grafting from" process by atom ... [more ▼]

This paper aims at reporting on the synthesis of a heterograft copolymer by combining the "grafting onto" process based on atom transfer radical addition (ATRA) and the "grafting from" process by atom transfer radical polymerization (ATRP). The statistical copolymerization of epsilon-caprolactone (epsilon-CL) and alpha-chloro-epsilon-caprolactone (alpha-Cl-epsilon-CL) was initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP), followed by ATRA of parts of the chlorinated units of poly(alpha-Cl-epsilon-CL-co-epsilon CL) on the terminal double bond of alpha-MeO,omega-CH2=CH-CH2-CO2-poly(ethylene oxide) (PEO). The amphiphilic poly(epsilon CL-g-EO) graft copolymer collected at this stage forms micelles as supported by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The unreacted pendant chloro groups of poly(epsilon-CL-g-EO) were used to initiate the ATRP of styrene with formation of copolymer with two populations of randomly distributed grafts, that is PEO and polystyrene [less ▲]

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See detailMacromolecular engineering of cyclic aliphatic polyesters by ring-opening polymerization
Lecomte, Philippe ULg; Riva, Raphaël ULg; Li, Haiying et al

Conference (2006, September 24)

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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 ▲]

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