References of "Lecomte, Philippe"
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See detailMetal-free strategies for the synthesis of functional and well-defined polyphosphoesters
Clement, Benoît ULg; Grignard, Bruno ULg; Koole, Leo et al

in Macromolecules (2012), 45(11), 4476-4486

We report here metal-free strategies using organocatalysis based on supramolecular recognition for the ring-opening polymerization (ROP) of several cyclic phosphate monomers (CPMs) by a variety of ... [more ▼]

We report here metal-free strategies using organocatalysis based on supramolecular recognition for the ring-opening polymerization (ROP) of several cyclic phosphate monomers (CPMs) by a variety of organocatalysts such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]undec-5-ene (TBD), and a bicomponent thiourea−tertiary amine catalyst. Each of these catalysts is efficient to produce linear polyphosphoesters (PPEs) from CPMs but with different sensitivity toward transesterification side reactions. The strong basicity of DBU is sufficient to activate an alcohol initiating the polymerization in the absence of any other cocatalyst. Nevertheless, side chain transfer reactions leading to branched and/or cyclic polymeric structures are observed, especially for high monomer conversion. Unlike DBU, TBD is a dual catalyst activating both the alcohol and the monomer. This dual activation allows shorter polymerization time, but SEC analyses of polyphosphates reveal bimodal molecular weight distribution due to chains coupling. Finally, a mixture of DBU and thiourea (TU) appears by far the most efficient catalyst to carry out fast and controlled polymerization while minimizing transesterification reactions, even at near-complete conversion. Compared with polymerizations carried out with Sn(Oct)2 as a metal catalyst, the control of polymerization is much better so that it is possible to prepare polyphosphoesters (PPEs) with molecular weight close to 70 000 g mol−1 and polydispersity index below 1.10. Simultaneous activation by TU of both CPMs and the alcohol group of the initiator by DBU proves to be an effective and robust ROP catalytic system to synthesize polymers with predictable molecular weight and narrow polydispersity. The chain extension experiments through the use of hydroxy end- capped PPEs as macroinitiators confirm the controlled/living nature of the DBU/TU-catalyzed ROP of CPMs and pave the way to the synthesis of block copolymers based on polyphosphates. [less ▲]

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See detailEasy functionalization of amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone) copolymer micelles with unprotected sugar: synthesis and recognition by lectins
Freichels, Hélène; Auzély-Velty, Rachel; Lecomte, Philippe ULg et al

in Polymer Chemistry (2012), 3(6), 1436-1145

This paper aims at reporting the end-functionalization of a PEO block of an amphiphilic α-acetal-PEO-b-PCL copolymer. The acetal end-group, which is the fragment of the initiator used in the EO ... [more ▼]

This paper aims at reporting the end-functionalization of a PEO block of an amphiphilic α-acetal-PEO-b-PCL copolymer. The acetal end-group, which is the fragment of the initiator used in the EO polymerization, was first hydrolyzed into an aldehyde that was then reacted with an amine by reductive amination reaction in water. This two-step derivatization was carried out in one pot. In a preliminary study a model amine, i.e. fluorescein amine, was used and the impact of the composition, thus of the Hydrophilic–Lipophilic Balance (HLB) of the amphiphilic copolymer, was studied. The experimental conditions were extended to the coupling of an aminated mannose to the diblock copolymer. The frozen micelles formed by the mannosylated copolymer proved to form complexes with various lectins as shown by Surface Plasmon Resonance (SPR) and Isothermal Titration Calorimetry (ITC). [less ▲]

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See detailSynthesis of new biomimetic biodegradable materials for clinical use
Clement, Benoît ULg; Grignard, Bruno ULg; Lecomte, Philippe ULg et al

Poster (2012, May 10)

For recent decades, the most commonly biodegradable polymers used in clinical and therapeutic applications are aliphatic polyesters such as polyglycolide, polylactide, polycaprolactone and their ... [more ▼]

For recent decades, the most commonly biodegradable polymers used in clinical and therapeutic applications are aliphatic polyesters such as polyglycolide, polylactide, polycaprolactone and their copolymers, mainly due to their excellent biocompatibility and biodegradability properties. However, the lack of functional groups on the backbone of polyesters, which could otherwise be used for tuning physicochemical properties and for introducing bioactive units, limits their further biomedical applications. Polymers with repeating phosphoester bonds in the backbone are structurally versatile and biodegradable through hydrolysis and possibly enzymatic digestion of phosphates linkages under physiological conditions. An advantage of polyphosphoesters (PPEs) compared to aliphatic polyesters is the possible functionalization of side chains due to the patenvalency of the phosphorous atom, allowing the introduction of bioactive molecules and extensive modification of the physical and chemical properties of final material. The Ring-Opening Polymerization (ROP) of cyclic esters is a well-established process to provide linear polyesters with predictable molecular weight, narrow polydispersity and well-defined end-groups. Up to now, metallic compounds are particularly used as initiators or polymerization catalysts to synthetize these materials but metallic derivatives are cytotoxic and a lack of residual metal contaminants is strongly required in view of biomedical applications. To tackle these drawbacks, we developed synthetic approaches that are metal-free (i.e., organocatalytic) using organocatalysis based on supramolecular recognition. A variety of organocatalysts such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]undec-5-ene (TBD) and a bicomponent thiourea-tertiary amine catalyst were studied. Each of these catalysts is efficient to produce linear polyphosphoesters (PPEs) from cyclic phosphate monomers (CPMs) but with different sensitivity towards transesterification side reactions. Compared with polymerizations carried out with Sn(Oct)2 as a metal catalyst, the control of polymerization is much better so that it is possible to prepare PPEs with molecular weight close to 70000 g.mol-1 and polydispersity index below 1.10. The chain extension experiments through the use of hydroxy end-capped PPEs as macro-initiators confirm the controlled/living nature of organo-catalyzed ROP of CPMs and pave the way to the synthesis of block copolymers based on polyphosphates. Finally, these polymerizations procedures are expected to facilitate the synthesis of well-defined PPEs with various architectures and free of potentially toxic metal remnants. The easy availability of catalysts, the mild conditions of polymerizations and the metal-free nature of the polymerizations makes these catalysts very attractive candidates for the synthesis of PPEs for biomedical applications such as drug and gene delivery, tissue engineering and dental applications. [less ▲]

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See detail"Click chemistry" to derived antimicrobial polymers
Lecomte, Philippe ULg; Riva, Raphaël ULg; Jérôme, Christine ULg

in Lagaron, José Maria; Ocio Zapata, Maria José; Lopez-Rubio, Amparo (Eds.) Antimicrobial polymers (2012)

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See detailRecent developments in ring-opening polymerization of lactones
Lecomte, Philippe ULg; Jérôme, Christine ULg

in Rieger, Bernhard; Künkel, Andreas; Coates, Geoffrey W. (Eds.) et al Synthetic Biodegradable Polymers (2012)

Polylactones are important biodegradable and biocompatible environmentally friendly polyesters widely used for many applications and more particularly for biomedical applications. This review covers ... [more ▼]

Polylactones are important biodegradable and biocompatible environmentally friendly polyesters widely used for many applications and more particularly for biomedical applications. This review covers recent advances dealing with their synthesis by ring-opening polymerization (ROP). First, lactones polymerized by ROP will be reviewed with special attention paid to the effect of the ring size on polymerizability. Aliphatic polyesters synthesized by the ROP of lactones can also be obtained by polycondensation. The advantages of ROP compared with polycondensation will be highlighted. The second section is devoted to the different mechanisms used to carry out ROP, such as anionic, coordination, cationic, enzymatic, and organocatalytic polymerization. Special attention will be paid to the control imparted to the polymerization by the use of catalysts and initiators. The polymerization of lactones substituted by functional groups will be shown to afford functionalized aliphatic polyesters. The final section will focus on the synthesis of different architectures such as star-shaped, graft, hyperbranched, and macrocyclic polylactones in the frame of macromolecular engineering. [less ▲]

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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 ▲]

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See detailStainless steel with robust anibacterial activiy based on a versatile and bio-inspired strategy
Faure, Emilie ULg; Lecomte, Philippe ULg; Vreuls, Christelle ULg et al

Conference (2011, September 01)

The synthesis of a poly(methacrylamide) bearing 3,4-dihydroxyphenylalanine inspired from the chemical composition of mussel adhesives will be presented. This homopolymer is designed to insure a multilayer ... [more ▼]

The synthesis of a poly(methacrylamide) bearing 3,4-dihydroxyphenylalanine inspired from the chemical composition of mussel adhesives will be presented. This homopolymer is designed to insure a multilayer film growth by covalent coupling during the layer-by-layer building with a homopolymer containing amino groups. The film cross-linking is initiated by adequately controlling both the redox state of the polymer and the pH of the solutions. This cross-linking is evidenced by solid-state 13C NMR with the occurrence of a typical signal of imine, traducing the Schiff base formation during film growth. The same coupling reaction is implemented for grafting an antibacterial peptide, Nisin, on a stainless steel substrate. Antibacterial activity against Bacillus subtilis is preserved even after long immersion time, as the result of the peptide covalent anchoring on the surface. All the processing steps, including the synthesis of the polymers and the peptide grafting, are performed in aqueous solutions under mild conditions. [less ▲]

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See detailSustainable and bio-inspired chemistry for robust antibacterial activity of stainless steel
Faure, Emilie ULg; Lecomte, Philippe ULg; Lenoir, Sandrine et al

in Journal of Materials Chemistry (2011), 21(22), 7901-7904

We report on the original synthesis of a poly(methacrylamide) bearing (oxidized) 3,4-dihydroxyphenylalanine specially designed to (i) insure film growth by covalent coupling, (ii) covalently bind an ... [more ▼]

We report on the original synthesis of a poly(methacrylamide) bearing (oxidized) 3,4-dihydroxyphenylalanine specially designed to (i) insure film growth by covalent coupling, (ii) covalently bind an antibacterial peptide and (iii) contribute to the film cross-linking that is essential for the durability of the properties. [less ▲]

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See detailPreparation of pH-sensitive star-shaped aliphatic polyesters as precursors of polymersomes
Riva, Raphaël ULg; Lazzari, Wenda; Billiet, Leen et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2011), 49(7), 1552-1563

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when ... [more ▼]

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when protonated at pH = 5.5. The copper mediated azide-alkyne cycloaddition was used for the synthesis of the star copolyester and to impart the pH sensitivity to the hydrophilic arm by grafting of tertiary amine groups onto azide bearing PCL chain. The formation of polymersomes in water at pH 5 was assessed by DLS and TEM analyses. [less ▲]

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See detailFluorescent labeling of degradable poly(lactide-co-glycolide) for cellular nanoparticles tracking in living cells
Freichels, Hélène; Danhier, Fabienne; Préat, Véronique et al

in International Journal of Artificial Organs (2011), 34(2), 152-160

Fluorescent-labeled aliphatic polyesters are essential materials for in vitro and in vivo studies of the behavior of these biodegradable polymers in interaction with cells or in a body. In particular, the ... [more ▼]

Fluorescent-labeled aliphatic polyesters are essential materials for in vitro and in vivo studies of the behavior of these biodegradable polymers in interaction with cells or in a body. In particular, the direct cellular localization of drug delivery systems based on these materials allows better understanding of the internalization mechanism and determination of the pharmacokinetics. Polylactide-co-glycolide (PLGA) is a rapidly degradable copolymer widely used in pharmaceutics and nanomedecine. It was prepared by ring-opening polymerization of lactide and glycolide in order to obtain a well-defined material to investigate conditions allowing the covalent linkage of a fluorescent dye (fluorescein) while preserving the macromolecular characteristics of the polymer. The success of the functionalization was ascertained by proton nuclear magnetic resonance (1H NMR), size-exclusion chromatography (SEC) and fluorescence spectroscopy. [less ▲]

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See detailContribution of "click chemistry" to the macromolecular engineering of aliphatic polyesters
Riva, Raphaël ULg; Schmeits, Stephanie ULg; Croisier, Florence ULg et al

Poster (2010, July 13)

In this work, click chemistry was sucessfully applied to the chemical modification of aliphatic polyesters with the purpose to tailor their physical properties. The developped strategy was then applied to ... [more ▼]

In this work, click chemistry was sucessfully applied to the chemical modification of aliphatic polyesters with the purpose to tailor their physical properties. The developped strategy was then applied to the synthesis of materials, such as smart partially degradable hydrogels or antibacterial polyesters. Last, the synthesis of amphiphilic star-shaped copolyester was investigated. [less ▲]

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See detailRecent development in the macromolecular engineering of functionalized aliphatic polyesters
Lecomte, Philippe ULg

Scientific conference (2009, December 16)

Detailed reference viewed: 31 (7 ULg)