Atom transfer radical polymerization of MMA with a macromolecular ligand in a fluorinated solvent and in supercritical carbon dioxide

in European Polymer Journal (2008), 44(3), 861-871

Macromolecular fluorinated ligands were prepared according to a three-step strategy that consists of the random copolymerization of heptadecafluorodecyl acrylate and 2-hydroxyethylacrylate, followed by ... [more ▼]

Macromolecular fluorinated ligands were prepared according to a three-step strategy that consists of the random copolymerization of heptadecafluorodecyl acrylate and 2-hydroxyethylacrylate, followed by the esterification of the pendant hydroxyl groups with acryloyl chloride and the Michael-type addition of tetraethyldiethylenetriamine onto the acrylic double bonds of the polymeric chains. These fluorinated macroligands were successfully used in the atom transfer radical polymerization of MMA catalyzed by a copper salt in a fluorinated solvent. The polymerization control was analyzed in relation to the copper salt, the initiator and the molecular weight and composition of the macroligand before being extended to the heterogeneous ATRP of MMA in scCO2. [less ▲]

PH-responsive biodegradable amphiphilic networks

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

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

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

Magnetic nanoparticles coated by temperature responsive copolymers for hyperthermia

in Journal of Materials Chemistry (2008), 18(28), 3352-3360

Various temperature-responsive N-isopropylacrylamide-based functional copolymers were prepared and used for the stabilization of iron oxide nanoparticles. The copolymers investigated are poly(acrylic acid ... [more ▼]

Various temperature-responsive N-isopropylacrylamide-based functional copolymers were prepared and used for the stabilization of iron oxide nanoparticles. The copolymers investigated are poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PAA-PNIPAM) and poly(acrylic acid)-b-poly(N-isopropylacrylamide)-b-poly(acrylate methoxy poly(ethylene oxide)) (PAA-PNIPAM-PAMPEO), with different molecular weights. The coated nanoparticles were characterized in terms of size by a combination of dynamic light scattering (DLS) and transmission electron microscopy (TEM). A sharp temperature transition was confirmed by particle size measurements vs. temperature. In addition, the stealthiness of the coated nanoparticles has been assessed in vitro by the haemolytic CH50 test. These measurements evidenced the crucial role of the PEO segments on the stealthiness of the nanoparticles and thus that such copolymers are particularly suitable for biomedical applications. Preliminary experiments of alternating magnetic field induced heating were performed and specific absorption rates of the various samples were recorded. [less ▲]

Metal-coordination: an effective lever for cobalt-mediated radical polymerization

in Polymer Preprints (2008), 49(27), 193-194

XRD and NMR characterization of synthetic hectorites and the corresponding surfactant-exchanged clays

in Clay Minerals (2008), 43

Functional amphiphilic and biodegradable copolymers for intravenous vectorization

in Polymer (2007), 48

This paper aims at reporting on the design of polymeric drug nanocarriers used in cancer therapy, with a special emphasis on the control of their biodistribution. First, the prominent role of poly ... [more ▼]

This paper aims at reporting on the design of polymeric drug nanocarriers used in cancer therapy, with a special emphasis on the control of their biodistribution. First, the prominent role of poly(ethylene oxide) in the lifetime of nanocarriers circulating in the blood stream is highlighted, and the origin of a passive targeting based on a difference in the anatomy of tumors and normal tissues is discussed. The main body of the review is devoted to the targeting of nanocarriers towards tumors and the underlying concepts. As a rule, either the constitutive polymer is stimuli-responsive and the locus of drug release is where the stimulation occurs, or a ligand endowed with specific recognition is grafted onto the nanocarrier. Finally, the fate of the nanocarrier after drug delivery and the bioelimination of the polymer(s) involved are briefly considered. [less ▲]

PEGylated quaternized copolymer/DNA complexes for gene delivery

in International Journal of Pharmaceutics (2007), 344(1-2), 88-95

The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and ... [more ▼]

The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and quaternized epsilon-caprolactone. For this purpose, diblock 50/50 copolymer was used to generate complexes-with DNA by either the solvent evaporation technique and by dialysis. The size, surface charge and degree of interaction of the plasmid-loaded formulations were measured. Then, polyplexes were combined with a poly(CL)-b-PEG copolymer to create a hydrophilic corona on the surface of the complexes. The cytotoxicity, transfection efficiency and cellular uptake of polyplexes and their association with PEG were evaluated on HeLa cells. The dialysis method did not allow to reduce the size of complexes as compared to the solvent evaporation method. The zeta potential of polyplexes became positive from a charge ratio of 4. The degree of interaction of copolymer with plasmid DNA was very high. Cytotoxicity and transfection efficiency were found to be comparable to polyethylenimine 50 kDa. Association of polyplexes with poly(CL)-b-PEG copolymer led to a small increase in particle size and a sharp decrease of charge surface. Cytotoxicity, transfection efficiency and cellular uptake were significantly reduced relative to unshielded copolymer/DNA complexes. The PEGylated formulations may be an attractive approach for an in vivo application. [less ▲]

Fast multiresponsive micellar gels from a smart ABC triblock copolymer

in Angewandte Chemie (International ed. in English) (2007), 46(42), 7988-7992

The triblock copolymer PS-b-P2VP-b-PEO undergoes simultaneous micellization and gelation, leading to high-storage-modulus materials that have fast responses to pH value, temperature, ionic strength, and ... [more ▼]

The triblock copolymer PS-b-P2VP-b-PEO undergoes simultaneous micellization and gelation, leading to high-storage-modulus materials that have fast responses to pH value, temperature, ionic strength, and shearing. The gel has a hierarchical structure with spherical core-shell-corona micelles, which, in turn, pack closely into an ordered cubic structure. [less ▲]

Nanohybrides de fullerène C60 à base d'alcool poly(vinylique) et de poly(N-vinylpyrrolidone): synthèse, caractrisation et illustration de leur potentiel en photothérapie dynamique du cancer

Conference (2007, October 11)

Macromolecular engineering of cyclic aliphatic polyesters by ring-opening polymerization and "click" chemistry

Conference (2007, September 04)

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

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