References of "Riva, Raphaël"
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See detailReversible TAD chemistry as a convenient tool for the design of (re)processable PCL-based shape-memory materials
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

in Macromolecular Rapid Communications (in press)

A chemically cross-linked but remarkably (re)processable shape-memory polymer (SMP) is designed by cross-linking poly(ε -caprolactone) (PCL) stars via the efficient triazolinedione click chemistry, based ... [more ▼]

A chemically cross-linked but remarkably (re)processable shape-memory polymer (SMP) is designed by cross-linking poly(ε -caprolactone) (PCL) stars via the efficient triazolinedione click chemistry, based on the very fast and reversible Alder– ene reaction of 1,2,4-triazoline-3,5-dione (TAD) with indole compounds. Typically, a six-arm star-shaped PCL function- alized by indole moieties at the chain ends is melt-blended with a bisfunctional TAD, directly resulting in a cross-linked PCL-based SMP without the need of post-curing treatment. As demonstrated by the stress relaxation measurement, the labile character of the TAD–indole adducts under stress allows for the solid-state plasticity reprocessing of the permanent shape at will by compression molding of the raw cross-linked material, while keeping excellent shape-memory properties. [less ▲]

Detailed reference viewed: 23 (10 ULg)
See detailOrganocatalytic ring-opening polymerization towards polyphosphoesters
Clément, Benoit; Vanslambrouck, Stépanie; Carion, Stéphan ULg et al

Conference (2016, September 13)

Hydrolytically degradable and biocompatible aliphatic polyesters are widely applied for biomedical applications as implants, scaffolds for tissue engineering and, finally, as nanocarriers for drug ... [more ▼]

Hydrolytically degradable and biocompatible aliphatic polyesters are widely applied for biomedical applications as implants, scaffolds for tissue engineering and, finally, as nanocarriers for drug delivery. Aliphatic phophoesters, known since the pioneering work of S. Penczek in the 70’s, exhibit the same properties of hydrolytic degradability and biocompatibility and are thus more and more studied for biomedical applications as well. In the field of materials, anti-fire properties opens up new perspectives. The difference between polyesters and polyphosphoesters in terms of synthesis and properties will be highlighted. Polyphosphosphoesters are synthesized by step-growth and chain growth polymerization. When these polyphosphoesters are synthesized by ring-opening polymerization of cyclic phosphoesters, organocatalysts turned out to be very efficient compared to coodination processes. The last part of the talk will deal with te implementation of ROP of cyclic phosphates towards a series of amphiphilic PEO-block-polyphosphate copolymers of tailored hydrophobicity depending on the length of the lateral alkyl group. These polymers are able to self assemble into nanoparticles by direct dissolution in water, thus in the absernce of any organic solvent. The so-obtained micelles were studied by a set of techniques (Pyrene Fluorescence, Dynamic Light Scattering, Tensiometry). Finally, the influence of the hydrophobicity of the polyphosphate block of the micelle on the encapsulation and the release of a model drug was investigated. [less ▲]

Detailed reference viewed: 43 (6 ULg)
See detailPolyphosphoester containing amphiphilic block copolymers as drug nanocarriers
Ergül, Zeynep ULg; Vanslambrouck, Stéphanie; Thiry, Justine ULg et al

Poster (2016, September 12)

The design of drug delivery systems often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, supramolecularly self-assembled ... [more ▼]

The design of drug delivery systems often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, supramolecularly self-assembled amphiphilic block copolymers into spherical micelles are appropriate carriers for poorly soluble drugs. In that framework, we have designed novel functional poly(ethylene oxide)-b-polyphosphoester amphiphilic block copolymers able to cross-linked under UV and degrade in response to a reduction of the pH from neutral conditions. Therefore, an unsaturated alkene side-chain was introduced on the cyclic phosphate monomer according to a one-step reaction followed by its organocatalyzed polymerization initiated by a poly(ethylene oxide) macroinitiator. After self-assembly into water, the micelles were cross-linked by UV irradiation. Then, these cross-linked micelles have been loaded by doxorubicin, i.e. a drug used in cancer therapy. We observed that the doxorubicin loading increased with the number of double bonds on the polyphosphate block of non-cross-linked micelles. This diblock amphiphilic copolymer bearing pendant unsaturations appears thus particularly promising candidate to build micellar drug delivery systems for intravenous injection. [less ▲]

Detailed reference viewed: 24 (2 ULg)
See detailPolyphosphoesters as a new platform for the design of particulate drug delivery systems
Vanslambrouck, Stéphanie; Ergul Yilmaz, Zeynep; Debuigne, Antoine ULg et al

Conference (2016, June)

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly ... [more ▼]

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly(lactide), the pentavalency of the phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendant groups. Therefore, macromolecular engineering of polyphosphoesters was applied to design well-defined architectures and functionalities adapted to drug nanocarriers. In a first approach, amphiphilic block copolymers are synthesized by organo-catalyzed ring-opening polymerization process for the synthesis of a range of PEO-b-polyphosphate bearing various pendant groups. Post-polymerization thiol-ene click reactions preformed on PEO-b-polyphosphate copolymers was also investigated to improve the hydrophobicity of the polyphosphate. The self-assembly of these PEO-b-polyphosphate copolymers into micelles was investigated, particularly, the effect of the nature of the polyphosphate pendant groups (i) on the micelles characteristics, (ii) on the encapsulation of a poorly soluble drug and (iii) on the drug release profile. The toxicity of the different amphiphilic block copolymers was also evaluated by live/dead cell viability assays. In a second approach, double hydrophilic copolymers based on polyphosphoesters have been used as templating agent for the synthesis of calcium carbonate particles. Indeed, the use of such microparticles is becoming more and more attractive in many fields especially for biomedical applications for which fine tuning of size, morphology and crystalline form of CaCO3 particles is crucial. Although some structuring compounds, like hyaluronic acid, give satisfying results, the control of the particle structure still has to be improved. To this end, we evaluated the CaCO3 structuring capacity of the well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and of a polyphosphoester segment with affinity for calcium like poly(phosphotriester)s bearing pendant carboxylic acids or poly(phosphodiester)s with a negatively charged oxygen atom on each repeating monomer unit. [less ▲]

Detailed reference viewed: 144 (12 ULg)
See detailPolyphosphoester containing amphiphilic block copolymers as drug nanocarriers
Yilmaz-Ergül, Zeynep ULg; Vanslambrouck, Stéphanie; Thiry, Justine ULg et al

Poster (2016, May 23)

The design of drug delivery systems (DDS) often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, poly(ethylene oxide)-b ... [more ▼]

The design of drug delivery systems (DDS) often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, poly(ethylene oxide)-b-polyphosphoester amphiphilic block copolymers are known to self-assemble into polymer micelles when placed in water are appropriate drug carriers. In this work, an unsaturated alkene side-chain was introduced on the cyclic phosphate monomer according to a one-step reaction followed by its organocatalyzed polymerization initiated by a poly(ethylene oxide) macroinitiator. After self-assembly into water, the micelles were cross-linked by UV irradiation. Then, these cross-linked micelles have been loaded by doxorubicin, which is a drug to use in cancer therapy. We observed that the doxorubicin loading increased with the number of double bonds on the polyphosphate block of non-cross-linked micelles. This diblock amphiphilic copolymer bearing pendant unsaturations appears thus particularly promising candidate to build micellar drug delivery systems for intravenous injection. [less ▲]

Detailed reference viewed: 46 (8 ULg)
See detailRecyclable shape-memory materials based on photo- or thermo-reversible reactions
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2016, February 16)

Shape-memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus ... [more ▼]

Shape-memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus, such as heat or light. Typically, the shape-memory property is generally observed for chemically or physically cross-linked polymers that exhibit an elastomeric behavior above a phase transition, e.g. glass or melting transition. As an example, cross-linked semi-crystalline poly(ε-caprolactone) (PCL) is widely studied for the development of SMPs. As most of SMPs are irreversibly cross-linked material, their reprocessing is impossible preventing any recycling. Thereby, reversible reactions, allowing the formation/cleavage of the network, raise tremendous interest for the development of new SMPs. Recently, we reported the preparation reversibly cross-linked PCL-based SMP using the Diels-Alder (DA) reaction between furan and maleimide end-groups of 4-arm star-shaped PCL, well-known to create reversible bonds. After implementation, this shape-memory material was demonstrated to be recyclable, and was characterized by excellent fixity and recovery before and after recycling experiments. However, the relatively low retro DA temperature of the furan-maleimide adducts led to an inelastic deformation during shape-memory tensile cycles. In order to get rid of this drawback, an alternative approach was investigated. The substitution of the DA reaction by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins, was proposed to prepare cross-linked PCL matrix presenting one-way and two-way memory properties, since photolabile adducts are supposed to be stable during shape-memory tensile cycles. [less ▲]

Detailed reference viewed: 62 (3 ULg)
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See detailComprehensive study of the thermo-reversibility of Diels-Alder based PCL polymer networks
Defize, Thomas ULg; Thomassin, Jean-Michel ULg; Alexandre, Michaël et al

in Polymer (2016), 84

Chemical crosslinking is an efficient tool to improve or impart new properties to conventional polymers. Especially, crosslinking imparts remarkable shapeememory properties to poly-ε-caprolactone (PCL ... [more ▼]

Chemical crosslinking is an efficient tool to improve or impart new properties to conventional polymers. Especially, crosslinking imparts remarkable shapeememory properties to poly-ε-caprolactone (PCL) materials. Nevertheless, the processing of networks is often tricky due to infusibility and insolubility of cross-linked chains. Therefore, the synthesis of PCL networks including thermo-reversible crosslinks based on (retro)-Diels-Alder (DA) reaction were developed to allowpreserving the melt-processing while keeping the required mechanical properties below the melting point. This paper aims at studying in depth, such thermo-dependent network formation and stability. Besides conventional swelling experi- ments, Raman spectroscopy was revealed as a powerful tool to follow the formation of the DA adduct during the crosslinking. In combination with rheological measurements, we were able to determine the most appropriate temperatures to form the network (DA crosslinking) and to process it (retro-DA re- action) without degradation of the material. [less ▲]

Detailed reference viewed: 59 (6 ULg)
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See detailCore cross-linked micelles of polyphosphoester containing amphiphilic block copolymers as drug nanocarriers
Ergül, Zeynep ULg; Vanslambrouck, Stéphanie; Cajot, Sébastien et al

in RSC Advances (2016), 6(48), 42081-42088

Poly(ethylene oxide)-b-polyphosphoester amphiphilic block copolymers are known to self-assemble into polymer micelles when dissolved into water. This work aims at reporting on the improvement of the ... [more ▼]

Poly(ethylene oxide)-b-polyphosphoester amphiphilic block copolymers are known to self-assemble into polymer micelles when dissolved into water. This work aims at reporting on the improvement of the stability of the micelles at high dilution by crosslinking the hydrophobic polyphosphoester micellar core. Typically, an unsaturated alkene side-chain was introduced on the cyclic phosphate monomer according to a one-step reaction followed by its organocatalyzed polymerization initiated by a poly(ethylene oxide) macroinitiator. This strategy avoids the use of any organometallic compounds in order to facilitate the purification and meet the stringent requirements of biomedical applications. After self-assembly into water, the micelles were cross-linked by simple UV irradiation. These cross-linked micelles have then been loaded by doxorubicin to evaluate their potential as drug nanocarriers and monitor the impact of crosslinking on the release profile. [less ▲]

Detailed reference viewed: 37 (15 ULg)
See detailSynthesis of functional polyphosphates for hydrogel and particle drug delivery systems
Vanslambrouck, Stéphanie; Ergül, Zeynep ULg; Clément, Benoit et al

Conference (2015, December 02)

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly ... [more ▼]

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly(lactide), the pentavalency of the phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendant groups. Macromolecular engineering of polyphosphoesters was applied to design well-defined architectures and functionalities adapted to drug nanocarriers. In a first approach, amphiphilic block copolymers are synthesized by organo-catalyzed ring-opening polymerization process for the synthesis of a range of PEO-b-polyphosphate bearing various pendant groups. Post-polymerization thiol-ene click reactions preformed on PEO-b-polyphosphate copolymers was also investigated to improve the hydrophobicity of the polyphosphate. The self-assembly of these PEO-b-polyphosphate copolymers into micelles was investigated, particularly, the effect of the nature of the polyphosphate pendant groups (i) on the micelles characteristics, (ii) on the encapsulation of a poorly soluble drug and (iii) on the drug release profile. The toxicity of the different amphiphilic block copolymers was also evaluated by live/dead cell viability assays. In a second approach, double hydrophilic copolymers based on polyphosphoesters have been used as templating agent for the synthesis of calcium carbonate particles. Indeed, the use of such microparticles is becoming more and more attractive in many fields especially for biomedical applications for which fine tuning of size, morphology and crystalline form of CaCO3 particles is crucial. Although some structuring compounds, like hyaluronic acid, give satisfying results, the control of the particle structure still has to be improved. To this end, we evaluated the CaCO3 structuring capacity of the well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and of a polyphosphoester segment with affinity for calcium like poly(phosphotriester)s bearing pendant carboxylic acids or poly(phosphodiester)s with a negatively charged oxygen atom on each repeating monomer unit. [less ▲]

Detailed reference viewed: 87 (8 ULg)
See detailDevelopment of photo- or thermo-reversible cross-linked recyclable shape-memory materials
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Conference (2015, September 01)

Shape-memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus ... [more ▼]

Shape-memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus, such as heat or light. Typically, the shape-memory property is generally observed for chemically or physically cross-linked polymers that exhibit an elastomeric behavior above a phase transition, e.g. glass or melting transition. As an example, cross-linked semi-crystalline poly(ε-caprolactone) (PCL) is widely studied for the development of SMPs. As most of SMPs are irreversibly cross-linked material, their reprocessing is impossible preventing any recycling. Thereby, reversible reactions, allowing the formation/cleavage of the network, raise tremendous interest for the development of new SMPs. Recently, we reported the preparation reversibly cross-linked PCL-based SMP using the Diels-Alder (DA) reaction between furan and maleimide end-groups of 4-arm star-shaped PCL, well-known to create reversible bonds. After implementation, this shape-memory material was demonstrated to be recyclable, and was characterized by excellent fixity and recovery before and after recycling experiments. However, the relatively low retro DA temperature of the furan-maleimide adducts led to an inelastic deformation during shape-memory tensile cycles. In order to get rid of this drawback, an alternative approach was investigated. The substitution of the DA reaction by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins, was proposed to prepare cross-linked PCL matrix presenting one-way and two-way memory properties, since photolabile adducts are supposed to be stable during shape-memory tensile cycles. [less ▲]

Detailed reference viewed: 81 (6 ULg)
See detailCross-linked polymer micelles made of polyphosphate containing amphiphilic copolymers for drug delivery
Riva, Raphaël ULg; Vanslambrouck, Stéphanie ULg; Ergül, Zeynep ULg et al

Conference (2015, September 01)

In the pharmaceutical field, amphiphilic block copolymers are of great interest for the nanovectorization of active principles in Drug Delivery. Indeed, new drugs are synthesized each day but in too many ... [more ▼]

In the pharmaceutical field, amphiphilic block copolymers are of great interest for the nanovectorization of active principles in Drug Delivery. Indeed, new drugs are synthesized each day but in too many cases, their high hydrophobicity makes them useless because of the absence of an appropriated administration method. Typically, amphiphilic block copolymers present the remarkable property to self-assemble in water with formation, in most cases, of spherical micelles characterized by a hydrophobic core and a hydrophylic corona. Rapidly, their ability to encapsulate a hydrophobic drug in their hydrophiobic core was investigated to increase the solubility of the drug in aqueous media, prevent its degradation and decrease its toxicity. However, polymer micelles suffer of the main drawback to be unstable in diluted medium, leading to a premature release of the drug, when the concentration falls down the critical micellar concentration (CMC), which it is rapidly observed after intravenous injection. This work aims at reporting on the development of a drug delivery device based on a new amphiphilic block copolymers made of degradable polyphosphate and bioeliminable poly(ethylene oxide). Thanks to their biocompatibility, biodegradability and their structure similar to natural biomacromolecules, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, polyphosphate properties and functionality are easily tuned via the chemical nature of the lateral chains R. In order to get rid of the CMC, the crosslinking of the micelle’s core was realized by UV radiation, in order to fulfill the increasingly stringent requirements of biomedical applications. For this purpose, photo-cross-linkable groups were introduced on the polyphosphate backbone. The effect of the crosslinking rate on the drug loading and the drug release was evaluated using doxorubicin as model drug. [less ▲]

Detailed reference viewed: 336 (8 ULg)
See detailPhoto- and thermo-reversible crosslinked recyclable shape memory materials
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2015, July 02)

Shape memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus ... [more ▼]

Shape memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus; such as heat or light. Typically; the shape memory property is generally observed for chemically or physically cross-linked polymers that exhibit an elastomeric behavior above a phase transition; e.g. glass or melting transition. As an example; cross-linked semi-crystalline poly(ε-caprolactone) (PCL) is widely studied for the development of SMPs. As most of SMPs are irreversibly cross-linked material; their reprocessing is impossible preventing any recycling. Thereby; reversible reactions; allowing the formation/cleavage of the network; raise tremendous interest for the development of new SMPs. Recently, we reported the preparation reversibly cross-linked PCL-based SMP using the Diels-Alder (DA) reaction between furan and maleimide end-groups of 4-arm star-shaped PCL, well-known to create reversible bonds. After implementation, this shape memory material was demonstrated to be recyclable, and was characterized by excellent fixity and recovery before and after recycling experiments. However, the relatively low retro DA temperature of the furan-maleimide adducts led to an inelastic deformation during shape memory tensile cycles. In order to get rid of this drawback, an alternative approach was investigated. The substitution of the DA reaction by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins, was proposed to prepare cross-linked PCL matrix presenting one-way and two-way memory properties, since photolabile adducts are supposed to be stable during shape memory tensile cycles. [less ▲]

Detailed reference viewed: 98 (9 ULg)