References of "Jérôme, Christine"
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See detailCO2-based sustainable polymers: from CO2-sourced monomers to low CO2 emission foamed materials
Grignard, Bruno ULg; Gennen, Sandro ULg; Alves, Margot ULg et al

Conference (2016, April)

Due to concerns about the climate change combined with the decrease of fossil resources, the use of CO2 as a C1 feedstock for producing added value chemicals and materials has become a huge challenge in ... [more ▼]

Due to concerns about the climate change combined with the decrease of fossil resources, the use of CO2 as a C1 feedstock for producing added value chemicals and materials has become a huge challenge in academic laboratories and in industry. The coupling of CO2 with epoxide has emerged as one of the most promising way to convert CO2 into cyclic carbonates finding application as green solvents or electrolyte for batteries. Interestingly, these cyclic carbonates can also be valorised as monomers to produce new non-isocyanate polyurethanes by step-growth polymerization with amines. Polyurethane (PU) is one of the most important polymers in our everyday life with numerous applications such as thermosets, thermoplastics, elastomers, adhesives, sealants, coatings, rigid and flexible foams for wellness or acoustic and/or thermal insulation. In this talk, we will discuss the preparation of all green bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams with thermal insulation properties by using an eco-efficient process based on the supercritical carbon dioxide (scCO2) foaming technology. This talk will be divided in three sections: The synthesis of CO2-sourced cyclic carbonates by coupling CO2 with epoxides using a new highly-efficient bicomponent homogeneous organocatalyst combining the use of an ammonium salt as the catalyst and a fluorinated hydrogen bond donor activator that allows the fast and solvent-free coupling of CO2 with (biosourced) epoxides under mild experimental conditions. The synthesis of (bio- and) CO2-sourced isocyanates-free PUs by melt step-growth copolymerization, eliminating the toxicological issues associated to the conventional synthesis of polyurethanes from diols and isocyanates. The foaming of NIPUs by exploiting the scCO2 foaming technology. By finely choosing the appropriate CO2 impregnation and foaming conditions, thermally insulating CO2-blown microcellular NIPUs foams were produced. [less ▲]

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See detailNon-isocyanate polyurethanes from carbonated soybean oil Using monomeric or oligomeric diamines To achieve thermosets or thermoplastics
Poussard, Loïc; Mariage, J.; Grignard, Bruno ULg et al

in Macromolecules (2016), 49(6), 2162-2171

Fully bio- and CO2-sourced non-isocyanate polyurethanes (NIPUs) were synthesized by reaction of carbonated soybean oil (CSBO) either with biobased short diamines or amino-telechelic oligoamides derived ... [more ▼]

Fully bio- and CO2-sourced non-isocyanate polyurethanes (NIPUs) were synthesized by reaction of carbonated soybean oil (CSBO) either with biobased short diamines or amino-telechelic oligoamides derived from fatty acids to achieve respectively thermoset or thermoplastic NIPUs. Biobased carbonated vegetable oils were first obtained by metal-free coupling reactions of CO2 with epoxidized soybean oils under supercritical conditions (120 °C, 100 bar) before complete characterization by FTIR, 1H NMR, and electrospray ionization mass spectroscopy (ESI-MS). In a second step, biobased NIPUs were produced by melt-blending of the so-produced cyclocarbonated oil with the biobased aminated derivatives. The thermal and mechanical properties of resulting polymers were found to be depending on the cyclocarbonated vegetable oil/amine ratio. More precisely, short diamines and CSBO led to the formation of cross-linked NIPUs, and the resulting tensile and thermal properties were poor. In contrast, elastomeric NIPUs derived from oligoamides and CSBO exhibited a better rigidity, an improved elongation at break (εr up to 400%), and a higher thermal stability (T95 wt% > 350 °C) than those of starting oligoamides. These results are impressive and highlight the potentiality of this environmental friendly approach to prepare renewable NIPU materials of high performances. [less ▲]

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See detailTheoretical study of the organocatalyzed synthesis of NIPUs
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Poster (2016, March)

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See detailCarbon dioxide and vegetable oil for the synthesis of bio-based polymer precursors, theoretical study of the organocatalyzed synthesis of non-isocyanate polyurethanes
Alves, Margot ULg; Jérôme, Christine ULg; Tassaing, Thierry

Conference (2016, March)

Non-isocyanate polyurethanes (NIPUs) represent a green alternative to the classical synthesis route of polyurethanes involving toxic isocyanates. This “greener” approach based upon renewable feedstocks ... [more ▼]

Non-isocyanate polyurethanes (NIPUs) represent a green alternative to the classical synthesis route of polyurethanes involving toxic isocyanates. This “greener” approach based upon renewable feedstocks and carbon dioxide consists in a two-step reaction. In a first step, carbonated vegetable oils are obtained using an appropriate catalyst by the chemical fixation of CO2 onto vegetable oils formerly epoxidized. Finally, the ring-opening polymerization (ROP) of the carbonated vegetable oil by a diamine provides hydroxy urethanes. In this las step, some organocatalysts have been recently proposed that allows achieving good conversion rates in particular in the case of aromatic diamines. However, the activation mechanism of these organocatalysts is not fully elucidated. In this context, the aim of the present project relies on the theoretical study of a model reaction using DFT calculations. Bicyclic guanidine based catalysts, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyl-TBD (MTBD), were investigated as catalysts for the reaction between propylene carbonate and aliphatic or aromatic amines. The structural ability of TBD to simultaneously give and receive protons was highlighted by the detailed mechanism investigation. The bifunctional activity 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 detailCobalt-mediated radical polymerization of vinyl acetate and acrylonitrile in supercritical carbon dioxide
Kermagoret; Chau, Ngoc Do Quyen; Grignard, Bruno ULg et al

in Macromolecular Rapid Communications (2016), 39(6), 539-544

Cobalt-mediated radical polymerization (CMRP) of vinyl acetate (VAc) is successfully achieved in supercritical carbon dioxide (scCO 2 ). CMRP of VAc is conducted using an alkyl-cobalt(III) adduct that is ... [more ▼]

Cobalt-mediated radical polymerization (CMRP) of vinyl acetate (VAc) is successfully achieved in supercritical carbon dioxide (scCO 2 ). CMRP of VAc is conducted using an alkyl-cobalt(III) adduct that is soluble in scCO2 . Kinetics studies coupled to visual observations of the polymerization medium highlight that the melt viscosity and PVAc molar mass ( Mn ) are key parameters that affect the CMRP in scCO2. It is noticed that CMRP is controlled for M n up to 10 000 g mol−1 , but loss of control is progressively observed for higher molar masses when PVAc precipitates in the polymerization medium. Low molar mass PVAc macroinitiator, prepared by CMRP in scCO2 , is then successfully used to initiate the acrylonitrile polymerization. PVAc-b-PAN block copolymer is collected as a free flowing powder at the end of the process although the dispersity of the copolymer increases with the reaction time. Although optimization is required to decrease the dispersity of the polymer formed, this CMRP process opens new perspectives for macromolecular engineering in scCO2 without the utilization of fluorinated comonomers or organic solvents. [less ▲]

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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 ▲]

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See detailSolubility and speciation of ketoprofen and aspirin in supercritical CO2 by infrared spectroscopy
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

in Journal of Chemical & Engineering Data (2016), 61(2), 968-978

The solubility of ketoprofen and aspirin in subcritical and supercritical CO2 was measured using FTIR absorption spectroscopy in the large range of temperature of 298.2−353.2 K and pressure of 5−35 MPa ... [more ▼]

The solubility of ketoprofen and aspirin in subcritical and supercritical CO2 was measured using FTIR absorption spectroscopy in the large range of temperature of 298.2−353.2 K and pressure of 5−35 MPa. The evolution of the solubility of both active pharmaceutical ingredients (APIs) was fitted using the Chrastil’s equation. In addition, the speciation of both APIs in monomeric and dimeric forms was explored by analyzing the characteristic carbonyl stretching vibrations of the carboxylic acid functions assigned to the dimers and monomers, respectively. Moreover, the evolution of the dimerization constant K of the two drugs as a function of the temperature and the pressure of scCO2 has been reported. [less ▲]

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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 ▲]

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See detailFar beyond primary poly(vinylamine)s through free radical copolymerization and amide hydrolysis
Dréan, Mathilde ULg; Guégan, Philippe; Jérôme, Christine ULg et al

in Polymer Chemistry (2016), 7(1), 69-78

Due to their affinity for many supports, their pH responsiveness, metal binding capacity and polyelectro- lyte complexation, poly(vinylamine) derivatives have attracted attention for many applications ... [more ▼]

Due to their affinity for many supports, their pH responsiveness, metal binding capacity and polyelectro- lyte complexation, poly(vinylamine) derivatives have attracted attention for many applications including coatings, water purification, or gas membrane separation. Nevertheless, most of them possess only pendant primary amines despite the possible benefits of incorporating different amino groups along the chain. In this work, a straightforward and scalable synthesis route towards polymers bearing primary and secondary amines, as well as imidazole groups, is reported. The general strategy relies on the radical copolymerization of different vinylamides and vinyl imidazoles followed by the hydrolysis of the resulting poly(vinylamide) derivatives. Binary and ternary free radical copolymerizations of N-vinylacetamide (NVA), N-methyl vinylacetamide (NMVA) and 1-vinylimidazole (VIm) were investigated and the reactivity ratios for each copolymerization system were determined. Thanks to these values a series of statistical copolymers with predictable composition and low deviation over the chain distribution could then be synthesized. Finally, the acidic hydrolysis of the acetamide functions towards the corresponding amine was performed and optimized. Copolymers containing various pendant amino groups and with low dispersity in the chain composition could be obtained, which opens new perspectives for the above mentioned applications. [less ▲]

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See detailOne-pot synthesis of double poly(ionic liquid) block copolymers by cobalt-mediated radical polymerization-induced self assembly (CMR-PISA) in water
Cordella, Daniela ULg; Debuigne, Antoine ULg; Jérôme, Christine ULg et al

in Macromolecular Rapid Communications (2016), 37(14), 1181-1187

Amphiphilic double poly(ionic liquid) (PIL) block copolymers are directly prepared by cobalt- mediated radical polymerization induced self-assembly (CMR-PISA) in water of N-vinyl imida- zolium monomers ... [more ▼]

Amphiphilic double poly(ionic liquid) (PIL) block copolymers are directly prepared by cobalt- mediated radical polymerization induced self-assembly (CMR-PISA) in water of N-vinyl imida- zolium monomers carrying distinct alkyl chains. The cobalt-mediated radical polymerization of N-vinyl-3-ethyl imidazolium bromide (VEtImBr) is first carried out until high conversion in water at 30 °C, using an alkyl bis(acetylacetonate)cobalt(III) adduct as initiator and con- trolling agent. The as-obtained hydrophilic poly(N-vinyl-3- ethyl imidazolium bromide) (PVEtImBr) is then used as a macroinitiator for the CMR-PISA of N-vinyl-3-octyl imidazo- lium bromide (VOcImBr). Self-assembly of the amphiphilic PVEtImBr-b-PVOcImBr block copolymer, i.e., of PIL-b-PIL-type, rapidly takes place in water, forming polymer nanoparticles consisting of a hydrophilic PVEtImBr corona and a hydro- phobic PVOcImBr core. Preliminary investigation into the effect of the size of the hydrophobic block on the dimension of the nanoparticles is also described. [less ▲]

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See detailA comprehensive density functional theory study of the key role of fluorination and dual hydrogen bonding in the activation of the epoxide/CO2 coupling by fluorinated alcohols
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

in RSC Advances (2016), 6(43), 36327-36335

The activation mechanism of the CO2/propylene oxide coupling catalysed by a bicomponent organocatalyst combining the use of TBABr with (multi)phenolic or fluorinated hydrogen bond donors (HBDs) was ... [more ▼]

The activation mechanism of the CO2/propylene oxide coupling catalysed by a bicomponent organocatalyst combining the use of TBABr with (multi)phenolic or fluorinated hydrogen bond donors (HBDs) was investigated using the Density Functional Theory (DFT). Thus, it was shown that increasing the number of electron withdrawing trifluoromethyl substituents in HBDs strengthens their proton donor capability and allows a better stabilization by hydrogen bonding of the intermediates and transition states. In addition, the high efficiency of fluorinated monoalcohol activators is related to a dual hydrogen bonding mechanism by two fluorinated molecules that cooperatively contribute to the CO2/propylene oxide coupling. [less ▲]

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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 ▲]

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See detailOrganocatalytic coupling of carbon dioxide with epoxides: the unexpected booster effect of fluoroalcohols
Grignard, Bruno ULg; Gennen, Sandro ULg; Alves, Margot ULg et al

Poster (2015, December 19)

Valorising CO2 as a C1 feedstock for producing added value building blocks is seducing as it is a free and in exhaustive waste resulting from human activity. Carbon dioxide is a thermodynamically and ... [more ▼]

Valorising CO2 as a C1 feedstock for producing added value building blocks is seducing as it is a free and in exhaustive waste resulting from human activity. Carbon dioxide is a thermodynamically and kinetically stable molecule that can be converted into cyclic carbonates by coupling with epoxides. Cyclic carbonates are valuable products that find applications as solvents, electrolytes or as monomers for polyurethanes synthesis. Although the CO2/epoxide coupling reaction has been extensively studied, the development of organocatalysts that are highly efficient under mild experimental conditions still remains a challenge. Onium salts are the most common catalysts that show reasonable catalytic activity at high pressure (> 100 bars) and high temperature (> 100°C) only. Fortunately, the efficiency of these organocatalysts can be improved by addition of appropriate hydrogen bond donors activators (HBD). In this talk, we will report the development of a new highly efficient catalytic platform consisting in an onium halide salt combined with HBD activators for the fast and solvent-free synthesis of cyclic carbonates by coupling CO2 with epoxides. The cocatalytic effect of series of HBDs will be demonstrated by detailed online kinetics studies under pressure using Raman or IR spectroscopy. We will show that our new organocatalytic platform facilitates the fast conversion of epoxy groups into cyclic carbonates under mild experimental conditions, and can be easily implemented to the modification of epoxidized vegetable oils. The synergistic effects between HBDs and onium salt will be highlighted by a detailed mechanistic study of the reaction through DFT calculations. [less ▲]

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See detailOrganometallic-mediated radical polymerization, a versatile tool for the precision synthesis of unprecedented copolymers
Detrembleur, Christophe ULg; Cordella, Daniela ULg; Demarteau, Jérémy ULg et al

Conference (2015, December 17)

Controlled radical polymerization techniques give access to innovative (multi)functional polymeric materials for advanced applications. Organometallic-mediated radical polymerization (OMRP) is one of ... [more ▼]

Controlled radical polymerization techniques give access to innovative (multi)functional polymeric materials for advanced applications. Organometallic-mediated radical polymerization (OMRP) is one of these techniques that enable the preparation of unprecedented copolymers, and is based on the temporary deactivation of the propagating chains by a transition metal complex. The strength of the carbon-metal bond at the polymer chain-end is dictating the reactivity of the system. One of the most efficient OMRP process involves the commercially available Co(acac)2. Recent studies have demonstrated that the system reactivity is easily modulated by the addition of some molecules able to coordinate the cobalt complex, by tuning the temperature, or by UV irradiation. The facile modulation of the C-Co bond strength has enabled to control the polymerization of monomers of opposite reactivity, such as vinyl esters and acrylates, and to synthesize novel well-defined (co)polymers under very mild experimental conditions. In this talk, we will discuss some recent breakthroughs in the field that illustrate the huge potential of the process for the design of unique functional macromolecules. More precisely, we will describe the first control of the copolymerization of ethylene with a series of functional vinyl monomers under mild experimental conditions that leads to random copolymers with ethylene content up to 60 mol% and negligible chain branching. The first one-pot synthesis of novel ethylene-based block copolymers will also be discussed. Additionally, we will demonstrate the implementation of the OMRP process to aqueous based media by describing, amongst other examples, the precision synthesis of innovative functional (telechelic) poly(ionic liquid)s (PILs) in water. [less ▲]

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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 ▲]

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See detailDrug-polymer electrostatic complexes as new structuring agents for the formation of drug-loaded ordered mesoporous silica
Molina, Emilie; Warnant, Jérôme; Mathonnat, Mélody et al

in Langmuir (2015), 31(47), 12839-12844

Using aminoglycoside antibiotics as drug models, it was shown that electrostatic complexes between hydrophilic drugs and oppositely charged double-hydrophilic block copolymers can form ordered mesophases ... [more ▼]

Using aminoglycoside antibiotics as drug models, it was shown that electrostatic complexes between hydrophilic drugs and oppositely charged double-hydrophilic block copolymers can form ordered mesophases. This phase behaviour was evidenced by using poly(acrylic acid)-block-poly(ethylene oxide) block copolymers in the presence of silica precursors and, this allowed preparing drug-loaded mesoporous silica directly from the drug-polymer complexes. The novel synthetic strategy of the hybrid materials is highly efficient, avoiding waste and multi-step processes; it also ensures optimal drug loading and provides pH-dependence of the drug release from the materials. [less ▲]

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See detailSynthesis of polyphosphodiesters by ring-opening polymerization of cyclic phosphates bearing allyl phosphoester protecting groups
Clément, Benoit; Molin, Daniel G.; Jérôme, Christine ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2015), 53(22), 2642-2648

The allyl phosphoester group is shown to be a protecting group for the synthesis of anionic polyphosphodiesters. Our strategy relies on the synthesis of a cyclic phosphate monomer bearing a pendant allyl ... [more ▼]

The allyl phosphoester group is shown to be a protecting group for the synthesis of anionic polyphosphodiesters. Our strategy relies on the synthesis of a cyclic phosphate monomer bearing a pendant allyl phosphoester group, its easy purification by fractional distillation, its organocatalyzed ring-opening polymerization by 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) and 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexyl-thiourea (TU). Finally, the deprotection of the allyl phosphoester group is carried out by reaction with sodium benzenethiolate in the absence of any detectable degradation. [less ▲]

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