References of "Jérôme, Christine"
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See detailSimple, cheap but highly efficient organo catalysts for the fixation of CO2 on propargylic alcohols
Ngassam Tounzoua, Charlene Gabriela ULg; Gilbert, Bernard ULg; Detrembleur, Christophe ULg et al

Poster (2017, May 04)

In the last years, many efforts have been devoted to the valorisation of CO2 as an abundant and renewable C1 building block for cyclic carbonate synthesis. Many synthetic routes have been proposed to ... [more ▼]

In the last years, many efforts have been devoted to the valorisation of CO2 as an abundant and renewable C1 building block for cyclic carbonate synthesis. Many synthetic routes have been proposed to convert CO2 into five or six-membered cyclic carbonates finding applications as green solvent, electrolytes for Li-ion batteries, intermediates for organic synthesis, monomers for the production of polycarbonates or isocyanate-free synthesis of poly(hydroxyrethane)s, etc. Although the 100% atom economy synthesis of 5-membered cyclic carbonates from CO2 and epoxides/oxetanes has been widely reported in the literature, the carboxylative coupling of CO2 with alkynols remains unexplored. Transition metal-based complexes, organic bases (guanidine, amidine, phosphine), N-heterocyclic carbenes or olefins, and K2CO3 have been proposed as catalysts. However they generally present sufficient activity at high pressure and/or temperature or require a high catalyst loading. Additionally some of them are toxic and/or sensitive to hydrolysis or oxidation. In this work, we designed novel, cheap, easily customizable and highly efficient organocatalysts for the synthesis of cyclic α-methylene carbonates from CO2 and alkynols. Kinetics of the CO2/alkynol coupling reaction were followed by Raman spectroscopy with organocatalysts of different structures, and the best candidate was identified. The main parameters that influenced the system reactivity and selectivity have been identified and will be presented in this poster. [less ▲]

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See detailSynthesis of well-defined polyvinylamine-containing copolymers via organometallic-mediated radical polymerization
Stiernet, Pierre ULg; Demarteau, Jérémy ULg; Jérôme, Christine ULg et al

Poster (2017, May 04)

Polyvinylamine (PVAm) is a useful polymer involved in a large range of applications including paper coating, surface engineering, membrane separation, etc. It is commonly produced via free radical ... [more ▼]

Polyvinylamine (PVAm) is a useful polymer involved in a large range of applications including paper coating, surface engineering, membrane separation, etc. It is commonly produced via free radical polymerization of N-vinylformamide (NVF) or N-vinylacetamide (NVA) followed by hydrolysis of the pendent amides of the resulting polymers. Due to the lack of stabilizing group on the double bond of N-vinylamides, the controlled radical polymerization of these monomers remained a challenge for a long time, preventing the preparation of well-defined PVAms. Recently, our group reported the controlled polymerization of NVA via reversible deactivation of the growing radical chains with cobalt complexes. Moreover, the use of well-defined PVAms as efficient carriers for gene transfection was demonstrated. This communication aims at reporting the synthesis of novel well-defined polyvinylamine-based copolymers. First, we explored the organometallic-mediated radical copolymerization of NVA and vinyl acetate. The optimized polymerization conditions and the comonomer reactivity ratios will be presented. Further conversion of the pendent amides and esters moieties into amino and hydroxy groups, respectively, was also considered for the preparation of unprecedented hydrophilic polyvinylamine-based copolymers. [less ▲]

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See detailPhoto-crosslinkable hydrogel for guided periodontal tissue regeneration
Chichiricco, Pauline Marie ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2017, May 04)

Periodontitis is an inflammatory disease resulting from the presence of oral bacteria biofilm in periodontal tissue, which destroys the tooth-supporting attachment apparatus. Untreated inflammation can ... [more ▼]

Periodontitis is an inflammatory disease resulting from the presence of oral bacteria biofilm in periodontal tissue, which destroys the tooth-supporting attachment apparatus. Untreated inflammation can spread to the gum tissue and lead, ultimately, to the loosening of the supporting tooth bone, with the risk that the tooth eventually falls. Guided Tissue Regeneration is a technique based on the application of a barrier membrane designed to prevent colonization of the wound space by epithelial cells from soft tissues. Indeed, these cells, characterized by a faster migration and proliferation rate compared to bone and periodontal ligament cells, could interfere with the regeneration process. In previously work Struillou et al. demonstrated the benefit effect of silated hydroxypropylmethylcellulose (Si HMPC)-based hydrogel can act as an efficient physical barrier in periodontal defect. Typically, this material is able to form a 3D network through the condensation of silanoate groups at physiological pH. However, a decrease of gelation time is necessary to assure the stability in peripheral part of the wound. In this project, we developed an injectable photo-crosslinkable membrane based on methacrylated carboxymethyl chitosan (CMCs) and Si HPMC that can be applied as a viscous solution and cured in situ in presence of a photoinitiator system made of riboflavin and triethanolamine. A visible light lamp (λ 420-480 nm), already used in dentistry, was preferred over a UV lamp. The addition of methacrylated polymer increase the stability of the material and increase the mass loss, in order to improve the bioresorption of the membrane. The chemical grafting of methacrylated carboxymethyl chitosan was characterized by 1H NMR and Infrared Spectroscopy. The gel point of the solution was determined by rheology and remained compatible with a clinical application. Moreover, the biocompatibility of this biomaterials was tested using murine cells using two assay: Neutral Red assay and MTT Cell Proliferation Assay. The in vitro tests validate the chemical synthesis in a biological point of view. The irradiation on cells and the direct contact with hydrogel doesn’t have an impact on cells viability. The capability of this material to act as a physical barrier was also evaluated using human gingival fibroblast. The cells were isolated from human gum explant before being put in contact with the hydrogel. After four days of contact no cells invasion was observed in the hydrogel using confocal microscopy. These preliminary results are quite promising for the development of novel injectable systems for Guided Periodontal Regeneration. In the future work, in vivo assays will be performed in Periodontal defect in a canine model. [less ▲]

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See detailReinforced poly(hydroxyurethane) coatings and high performance adhesive
Panchireddy, Satyannarayana ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Poster (2017, May 04)

Polyurethane (PU) is one of the most widely used polymeric materials and largely valorised in coating applications as paints or as adhesives. Because toxicity issues of isocyanates and changes in the ... [more ▼]

Polyurethane (PU) is one of the most widely used polymeric materials and largely valorised in coating applications as paints or as adhesives. Because toxicity issues of isocyanates and changes in the environmental and REACH regulations, there is a need today to develop new greener and safer alternatives to produce PU. One of the most promising way relies on the synthesis of polyurethane by a non-isocyanate route (NIPU) by copolymerization between a bicyclic carbonate monomers and a diamine. This study reports on the synthesis of new sustainable NIPU coatings for Al anti-corrosion protection and for metal adhesion. In a first step, (bio- and) CO2-sourced cyclic carbonates will be synthesized by coupling of multifunctional epoxides with CO2 using a new efficient bicomponent organocatalyst. In a second step, various cyclic carbonates/amines formulations were developed and cured in presence of fillers to produce reinforced NIPUs thermosets which anti-corrosion and adhesive properties are evaluated and benchmarked with existing formulations. Some formulations present outstanding adhesions to various substrates. [less ▲]

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See detailAll poly(ionic) liquid-based block copolymers incorporating fluorinated and triethyleneglycol units: direct synthesis in water and investigation as single-ion conductive solids
Ouhib, Farid ULg; Cordella, Daniela; Aqil, Abdelhafid ULg et al

Poster (2017, May 04)

Poly(ionic liquid)s (PILs) have attracted a considerable attention as innovative single-ion solid polyelectrolytes (SPEs) in substitution to the more conventional electrolytes for a variety of ... [more ▼]

Poly(ionic liquid)s (PILs) have attracted a considerable attention as innovative single-ion solid polyelectrolytes (SPEs) in substitution to the more conventional electrolytes for a variety of electrochemical devices. Imidazolium-based PILs are amongst the most investigated, because they are easy to synthesize and some of them have shown a good combination between high ionic conductivity, wide chemical and electrochemical stability, and good mechanical properties. Herein, we report the precise synthesis, characterization, and use as single-ion SPE of a novel double PIL-based amphiphilic diblock copolymer (BCP), i.e. where all monomer units are of N-vinyl-imidazolium-type, with triethylene glycol pendant groups in the first block, and a statistical distribution of N-vinyl-3-ethyl- and N-vinyl-3-perfluorooctyl-imidazolium bromides in the second block. BCP synthesis is achieved directly in water by a one-pot process, following the principle of the cobalt-mediated radical polymerization-induced self-assembly (CMR-PISA). A subsequent anion exchange reaction substituting bis(trifluoromethylsulfonyl)imide (Tf2N-) for bromide (Br-) counter-anions leads to the targeted PIL BCPs with two different lengths of the first block. They demonstrate ionic conductivity σDC = 1-3 10-7 S cm-1, as determined by broadband dielectric spectroscopy at 30 °C (under anhydrous conditions), and form free standing films with mechanical properties suited for SPE applications with Young’s modulus of 3.8 MPa and elongation at break of 250 % as determined by stress/strain experiments. [less ▲]

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See detailPhotosensitive polydimethylsiloxane networks for adjustable-patterned films
Jellali, Rachid; Alexandre, Michaël; Jérôme, Christine ULg

in Polymer Chemistry (2017), 8(16), 2499-2508

Polydimethylsiloxanes (PDMSs) bearing photoreactive coumarin groups have been synthesized by amida- tion of a coumarin acid chloride derivative with various amine-functionalized PDMSs. Upon exposure to UV ... [more ▼]

Polydimethylsiloxanes (PDMSs) bearing photoreactive coumarin groups have been synthesized by amida- tion of a coumarin acid chloride derivative with various amine-functionalized PDMSs. Upon exposure to UV light having a wavelength of above 300 nm, multifunctional coumarin-PDMSs are transformed into covalent networks via [2 + 2] photocycloaddition of two coumarin moieties forming a cyclobutane ring. Taking advantage of the possible localized irradiation through a photomask, a novel concept to generate patterned PDMS films with various surface topologies was demonstrated. This concept is based on the combination of a low molar mass difunctional PDMS with a multifunctional PDMS of a high molar mass forming a photoreversible network allowing osmotic diffusion of a linear PDMS-coumarin of low mole- cular weight in a loosely crosslinked network. Advantageously, illumination by a light source at 254 nm induces the photocleavage of the cyclobutane cross-links offering some photo-induced reversibility to the PDMS network. These novel photo-responsive networks are interesting for several applications, in photo-adaptable biomedical implants (particularly photo-adjustable intra-ocular lenses), photo-tuneable patterned microsystems (e.g. for microfluidics) and photo-switchable controlled release systems. [less ▲]

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See detailOrganometallic-mediated radical polymerization of 'less activated monomers': fundamentals, challenges and opportunities
Debuigne, Antoine ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg

in Polymer (2017), 115

Access to well-defined polymers made of the so-called ‘Less Activated Monomers’ (LAMs) via controlled radical polymerization has long been a challenge due to the lack of radical stabilizing group on the ... [more ▼]

Access to well-defined polymers made of the so-called ‘Less Activated Monomers’ (LAMs) via controlled radical polymerization has long been a challenge due to the lack of radical stabilizing group on the double bond of these monomers. This Feature Article summarizes substantial progress in the organometallic-mediated radical polymerization (OMRP) of this important class of monomers including vinyl esters, olefins, vinyl chloride, vinyl amides, or ionic-liquid vinyl monomers. It aims to provide a clear and comprehensive account of the fundamentals and challenges in the OMRP of LAMs as well as an overview of the resulting macromolecular engineering opportunities. The input of photochemistry, environmentally friendly solvents or flow reactors in OMRP is also presented. Finally, it emphasizes how some well-defined LAMs-based materials contributed to the development of specific applications notably in the fields of biomedicine or energy. [less ▲]

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See detailDFT investigation of the reaction mechanism for the guanidine catalyzed ring-opening of cyclic carbonates by aromatic and alkyl-amines
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

in RSC Advances (2017), 7(31), 18993-19001

The guanidine catalysed aminolysis of propylene carbonate has been investigated using the density functional theory (DFT) and highlights that different reaction pathways are involved depending on the ... [more ▼]

The guanidine catalysed aminolysis of propylene carbonate has been investigated using the density functional theory (DFT) and highlights that different reaction pathways are involved depending on the aromatic or aliphatic nature of the amine. The structural ability of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) to simultaneously give and receive protons was demonstrated by a detailed mechanistic investigation. The bifunctional activity (base/H-bond donor) of TBD significantly reduces the Gibbs energy of the reaction and allows understanding its higher efficiency compared to its methyl counterpart (MTBD). [less ▲]

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See detailOrganocatalytic coupling of CO2 with a propargylic alcohol: a comprehensive study of the reaction mechanism combining in- situ ATR-IR spectroscopy and DFT calculations
Boyaval, Amélie ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

in ChemSusChem (2017), 10(6), 1241-1248

The metal-free coupling of propargylic alcohols with carbon dioxide catalysed by guanidine derivatives was investigated in detail through the combination of online kinetic studies by in-situ ATR-IR ... [more ▼]

The metal-free coupling of propargylic alcohols with carbon dioxide catalysed by guanidine derivatives was investigated in detail through the combination of online kinetic studies by in-situ ATR-IR spectroscopy and DFT calculations. Bicyclic guanidines, namely TBD and MTBD, are effective catalysts for the conversion of 2-methyl-3-butyn-2-ol to α-methylene cyclic carbonate and oxoalkyl acyclic carbonate under mild reaction conditions. The lower selectivity of TBD in comparison with MTBD towards the formation of α-methylene cyclic carbonate was elucidated from DFT calculations and is related to the bifunctional activity (base/H-bond donor) of TBD decreasing the Gibbs free energy of the reaction path for the formation of the acyclic carbonate. Introduction [less ▲]

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See detailOrganocatalytic coupling of CO2 with oxetane
Alves, Margot ULg; Grignard, Bruno ULg; Boyaval, Amélie ULg et al

in ChemSusChem (2017), 10(6), 1128-1138

The organocatalytic coupling of CO2 with oxetanes is investigated under solvent-free conditions. The influence of the main reaction parameters (type of organocatalytic system, pressure and temperature) on ... [more ▼]

The organocatalytic coupling of CO2 with oxetanes is investigated under solvent-free conditions. The influence of the main reaction parameters (type of organocatalytic system, pressure and temperature) on the yield, the product formed and the selectivity of the reaction are discussed. An onium salt combined with a fluorinated alcohol promotes the efficient and selective organocatalytic synthesis of α,ω-hydroxyl oligocarbonates by coupling CO2 with oxetanes at 130 °C and at a CO2 pressure as low as 2 MPa. NMR characterizations were correlated with MALDI-ToF analyses for elucidating the structure of the oligomers. Online FTIR studies under pressure, NMR titrations and DFT calculations allowed an in-depth understanding of the reaction mechanism. Finally, CO2- based poly(carbonate-co-urethane)s were synthesized by step- growth polymerization of hydroxyl telechelic oligocarbonates with MDI. The organocatalytic system described in this paper constitutes an innovative sustainable route to the selective preparation of hydroxyl telechelic carbonates, of high interest for many applications, notably for the polyurethane business, especially for coatings or foams. [less ▲]

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See detailOils and CO2, a promising combination for designing insulating foams and high performance coatings
Detrembleur, Christophe ULg; Alves, Margot ULg; Grignard, Bruno ULg et al

Conference (2017, March 21)

Making plastics more sustainable by valorizing waste CO2 as a cheap, inexhaustible and renewable feedstock is an early stage technology with strong innovation potential that imposes itself as a strategic ... [more ▼]

Making plastics more sustainable by valorizing waste CO2 as a cheap, inexhaustible and renewable feedstock is an early stage technology with strong innovation potential that imposes itself as a strategic driver for developing future low carbon footprint materials and technologies. With a global production estimated to 18 million tons for 2016, polyurethane (PU) is one of the most important polymers in our everyday life applications (automotive, building and construction, coatings, etc.). Industrially, PU is produced by step-growth polymerization between di- or polyisocyanates and di- or polyols. However, isocyanates are toxic and drastic changes in the REACH regulations limiting/banning the use of isocyanates are expected. There is a need today to develop new greener and safer alternatives to produce PU. Valorizing CO2 as C1 feedstock for producing precursors entering in the synthesis of polyurethanes by a non-isocyanate route (NIPU) is a promising strategy to solve this challenge. In this talk, we will focus on the synthesis and characterization of novel NIPUs foams for thermal insulation, and NIPUs coatings for metal protection. Our research highlights benefit of merging bio-resources (such as vegetable oils) with carbon dioxide transformation. In the first part of this talk, we will report on the fast synthesis of bio- and CO2-sourced cyclic carbonates by coupling CO2 with epoxides using a new highly efficient bicomponent homogeneous organocatalyst under solvent-free and mild experimental conditions. The mechanism of the activation of the reaction will be discussed, and scaling up of the technology will be demonstrated (15kg scale). In the second part, we will illustrate the use of these bio- and CO2-sourced cyclic carbonates for the production of microcellular NIPU foams with closed cells morphology for thermal insulating applications, but also for preparing hybrid NIPUs coatings for metal protection. [less ▲]

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See detailSimultaneous synthesis and chemical functionalization of emulsion-templated porous polymers using nitroxide-terminated macromolecular surfactants
Mathieu, Kevin ULg; De Winter, Julien; Jérôme, Christine ULg et al

in Polymer Chemistry (2017), 8(11), 1850-1861

The design of functional 3D macroporous monoliths has become a necessity for a wide range of applications. Traditional post-modification strategies of porous materials are efficient but often consist in ... [more ▼]

The design of functional 3D macroporous monoliths has become a necessity for a wide range of applications. Traditional post-modification strategies of porous materials are efficient but often consist in tedious multi-steps processes. This work describes a straightforward macromolecular surfactant-assisted method for producing chemically functionalized macroporous polyHIPEs with interconnected structures. Accordingly, high internal phase emulsion-templated polymerizations were implemented in the presence of SG1-terminated amphiphilic copolymers prepared by nitroxide- mediated radical polymerization (NMP). The latter served as both stabilizers and functionalizing agents upon thermal activation of its terminal alkoxyamine and covalent anchoring of the released radical copolymer onto the walls of the scaffold. The effect of the polymerization temperature on the functionalization and openness of the final porous materials was explored. As a result, a range of open-cell styrene and acrylate-based polyHIPEs chemically grafted with PEO were obtained. Moreover, polyHIPEs were also decorated with alkyne-bearing PEO and subsequently modified via CuAAc click chemistry in order to demonstrate the potential of this macromolecular surfactants-assisted functionalization method. [less ▲]

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See detailEnolates in macromolecular science: current situation and future outlook
Lecomte, Philippe ULg; Jérôme, Christine ULg

in Zabicky, Jacob (Ed.) The Chemistry of Metal Enolates (Volume 2) (2017)

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See detailBioreducible cross-linked core polymer micelles enhance in vitro activity of methotrexate in breast cancer cells
Gulfam, Muhammad ULg; Matini, Teresa; Monteiro, Patrícia F et al

in Biomaterials Science (2017), 5(3), 532-550

Polymer micelles have emerged as promising carriers for controlled release applications, however, several limitations of micelle-based drug delivery have also been reported. To address these issues, we ... [more ▼]

Polymer micelles have emerged as promising carriers for controlled release applications, however, several limitations of micelle-based drug delivery have also been reported. To address these issues, we have synthesized a functional biodegradable and cytocompatible block copolymer based on methoxypoly (ethyleneglycol)-b-poly(ε-caprolactone-co-α-azido-ε-caprolactone) (mPEG-b-poly(εCL-co-αN3εCL)) as a precursor of reduction sensitive core-crosslinked micelles. The synthesized polymer was formulated as micelles using a dialysis method and loaded with the anti-inflammatory and anti-cancer drug metho- trexate (MTX). The micellar cores were subsequently crosslinked at their pendent azides by a redox- responsive bis(alkyne). The size distributions and morphology of the polymer micelles were assessed using dynamic light scattering (DLS) and transmission electron microscopy, and drug release assays were performed under simplified (serum free) physiological and reductive conditions. Cellular uptake studies in human breast cancer cells were performed using Oregon-green loaded core-crosslinked micelles. The MTX-loaded core-crosslinked micelles were assessed for their effects on metabolic activity in human breast cancer (MCF-7) cells by evaluating the reduction of the dye MTT 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide. The apoptosis inducing potential of MTX-loaded core-crosslinked micelles was analysed using Hoechst/propidium iodide (PI) and annexin-V/PI assays. The data from these experi- ments indicated that drug release from these cross-linked micelles can be controlled and that the redox- responsive micelles are more effective carriers for MTX than non-crosslinked analogues and the free drug in the cell-lines tested. [less ▲]

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See detailUse of primary and secondary polyvinylamines for efficient gene transfection
Dréan, Mathilde; Debuigne, Antoine ULg; Gonçalves, Christine et al

in Biomacromolecules (2017), 18(2), 440-441

Gene transfection with polymeric carrier remains a challenge, particularly high transfection levels combined with low toxicity are hard to achieve. We herein revisit polyvinylamines, an old and neglected ... [more ▼]

Gene transfection with polymeric carrier remains a challenge, particularly high transfection levels combined with low toxicity are hard to achieve. We herein revisit polyvinylamines, an old and neglected family of cationic polymers. They can be readily obtained by controlled hydrolysis of polyvinylamides prepared through (controlled) radical polymerization. A series of tailor-made and well-defined polyvinylamines bearing primary amino groups, and poly(N- methylvinylamine) bearing secondary amines, were evaluated for the transfection of cells with pDNA as a function of their molar mass, molar mass distribution and degree of deacetylation. Unexpected high transfection levels, in combination with low cytotoxicity were recorded for both series. Surprisingly, a great impact of the molar mass was observed for the primary amine polyvinylamine series, whereas the results were mostly independent on molar mass or dispersity for the polymer bearing secondary amine. It was further established that a certain percentage of acetamide groups increased the transfection level, while maintaining low cytotoxicity. These results highlight for the first time the real potential of polyvinylamines as gene carriers, and make these polymers very attractive for further development in gene therapy. [less ▲]

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See detailPhotocleavable stabilizer for the preparation of PHEMA nanogels by dispersion polymerization in supercritical carbon dioxide
Alaimo, David; Grignard, Bruno ULg; Kuppan, Chandrasekar et al

in Polymer Chemistry (2017), 8(3), 581-591

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a ... [more ▼]

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a light sensitive o- nitrobenzyl group was successfully synthesized by RAFT polymerization and used as stabilizer for the free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in dispersion in ?,?,?-trifluorotoluene and supercritical carbon dioxide (scCO2). Thanks to this fluorinated stabilizer, well-defined particles of PHEMA down to 350 nm of diameter were produced in scCO2. Advantageously, the photocleavable group at the block junction of the stabilizer could be cleaved by exposing the particles to UV light so that the fluorinated block could be extracted in TFT or scCO2. As supported by X-ray photoelectron spectroscopy (XPS) analysis, up to 80 % of the fluorinated block of the stabilizer can be removed, leading to efficient swelling and dispersion of the resulting PHEMA nanogels in water. [less ▲]

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See detailHot-Melt Extrusion as a Continuous Manufacturing Process to Form Ternary Cyclodextrin Inclusion Complexes
Thiry, Justine ULg; Krier, Fabrice; Ratwatte, Shenelka et al

in European Journal of Pharmaceutical Sciences (2017), 96

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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 (2017), 38(1), 1600517

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 ▲]

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See detailDevelopment and evaluation of injectable nanosized drug delivery systems for apigenin
Karim, Reatul ULg; Palazzo, Claudio ULg; Laloy, Julie et al

in International Journal of Pharmaceutics (2017)

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and ... [more ▼]

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and compare their characteristics to identify the nanovector(s) that can deliver the largest quantity of AG while being biocompatible. Two liposomes with different surface characteristics (cationic and anionic), a LNC and a PNC were prepared. A novel tocopherol modified poly(ethylene glycol)-b-polyphosphate block-copolymer was used for the first time for the PNC preparation. The NDDSs were compared by their physicochemical characteristics, AG release, storage stability, stability in serum, complement consumption and toxicity against a human macrovascular endothelial cell line (EAhy926). The diameter and surface charge of the NDDSs were comparable with previously reported injectable nanocarriers. The NDDSs showed good encapsulation efficiency and drug loading. Moreover, the NDDSs were stable during storage and in fetal bovine serum for extended periods, showed low complement consumption and were non-toxic to EAhy926 cells up to high concentrations. Therefore, they can be considered as potential injectable nanocarriers of AG. Due to less pronounced burst effect and extended release characteristics, the nanocapsules could be favorable approaches for achieving prolonged pharmacological activity of AG using injectable NDDS. [less ▲]

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See detailPhotoreversibility and biocompatibility of polydimethylsiloxane-coumarin as adjustable intraocular lens material
Jellali, Rachid; Bertrand, Virginie ULg; Alexandre, Michaël et al

in Macromolecular Bioscience (2017)

Polydimethylsiloxane (PDMS) constitutes an interesting material for a variety of biomed- ical applications, especially as intraocular lenses (IOLs), for its excellent transparency. In this work, a ... [more ▼]

Polydimethylsiloxane (PDMS) constitutes an interesting material for a variety of biomed- ical applications, especially as intraocular lenses (IOLs), for its excellent transparency. In this work, a photoreversible PDMS-coumarin network, whose shape and properties can be adjusted postoperatively in a noninvasive manner, is developed. The synthesis of PDMS-cou- marin is achieved by amidation of a coumarin acid chloride derivative with amine-function- alized PDMSs. Under exposure of λ > 300 nm, these polymers can be cured by dimerization of coumarin. The cured polymers can be uncrosslinked via photocleavage of cyclobutane dimers upon illumination at λ < 290 nm. The diffusion of linear PDMSs in a crosslinked network and the controlled shape modification are studied, which demonstrate that these polymers are good candidates for adjustable IOL application. IOL disks prepared from these materials show high hydrophobicity and good transparency. In vitro cytotoxicity, lens epithelial cell adhesion assays, and rabbit host reaction against implanted disks demonstrate the biocompatibility of the polymer. [less ▲]

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