Source: http://ipcm.fr/article647.html?lang=fr
Timestamp: 2019-04-18 16:58:06+00:00

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P. Biais, P. Beaunier, F. Stoffelbach, et J. Rieger, « Loop-stabilized BAB triblock copolymer morphologies by PISA in water », Polymer Chemistry, vol. 9, nᵒ 35, p. 4483-4491, sept. 2018.
Résumé : A straightforward strategy to synthesize loop-stabilized particles in water via PISA is developed. These particular structures can in theory be obtained through the synthesis of amphiphilic BAB triblock copolymers, starting from a hydrophilic middle block A, which is chain extended in an aqueous PISA process with two hydrophobic external blocks B. For this purpose, symmetrical bifunctional poly(N,N-dimethylacrylamide) macroRAFT agents with a central benzoic acid group and an alkyl chain as the Z group are used in the aqueous dispersion polymerization of diacetone acrylamide. For the first time, stable BAB flower-like particles are formed via PISA in pure water. It is shown that the colloidal stability and the resulting particle morphology (spheres, worms, vesicles) strongly depend on the degree of ionization of the central charge in the stabilizer loop, and thus on the pH at which PISA is performed. Moreover, the influence of the length of the alkyl Z group (dodecyl and butyl alkyl chains) on the colloidal stability is studied.
Mots-clés : POLE 4, POLYMERES.
R. Brisse, D. Guianvarc'h, C. Mansuy, S. Sagan, D. Kreher, L. Sosa-Vargas, L. Hamitouche, V. Humblot, I. Arfaoui, V. Labet, C. Paris, C. Petit, et A. - J. Attias, « Probing the in-air growth of large area of 3D functional structures into a 2D supramolecular nanoporous network », Chemical Communications, vol. 54, nᵒ 72, p. 10068-10071, 2018.
X. Callies, E. Ressouche, C. Fonteneau, G. Ducouret, S. Pensec, L. Bouteiller, et C. Creton, « Effect of the Strength of Stickers on Rheology and Adhesion of Supramolecular Center-Functionalized Polyisobutenes », Langmuir, vol. 34, nᵒ 42, p. 12625-12634, oct. 2018.
Résumé : In order to systematically investigate the effect of the strength of the supramolecular interactions on the debonding properties of associative polymers, a series of model systems have been characterized by probe-tack tests. These model materials, composed of linear and low dispersity poly(isobutylene) chains (Mn ≈ 3 kg/mol) center-functionalized by a single bis-urea sticker, are able to self-assemble by four hydrogen bonds. Three types of stickers are used in the present study: a bis-urea with a methylene diphenyl (MDI) spacer, a bis-urea with a tolyl (TOL) spacer, and a bis-urea with a xylyl (XYL) spacer. In order to investigate the influence of stickers in depth, both the nanostructure of the materials and the linear rheology were investigated by small-angle X-ray scattering (SAXS) and oscillatory shear, respectively. For two types of stickers (TOL and XYL), the association of polymers via hydrogen bonds induces the formation of bundles of rodlike aggregates at room temperature and the behavior of a soft elastic material was observed. For bis-urea MDI, no structure is detected by SAXS and a Newtonian behavior is observed at room temperature. In probe-tack experiments, all these materials show a cohesive mode of failure, a signature of flowing materials as previously observed for tri-urea center-functionalized poly(butylacrylate) (PnBA3U). However, XYL center-functionalized polyisobutene shows much higher debonding energies than PnBA3U, revealing the importance of the strength of noncovalent bonds in the scission/recombination dynamics. On the basis of the analysis of the debonding images, this effect is discussed via the mechanical behavior at large deformation.
M. Dréan, A. Debuigne, C. Jérôme, C. Goncalves, P. Midoux, J. Rieger, et P. Guégan, « Poly(N-methylvinylamine)-Based Copolymers for Improved Gene Transfection », Macromolecular Bioscience, vol. 18, nᵒ 4, p. 1700353, avr. 2018.
Résumé : Poly(N-methylvinylamines) with secondary amines can form complexes with plasmid DNA (pDNA) and provide transfection efficiency in HeLa cells in the same order as linear polyethyleneimine but with higher cell viability. Chemical modifications of poly(N-methylvinylamine) backbones are performed to further improve transfection efficiency while maintaining low degree of cytotoxicity. In a first type of polymer, primary amino groups are incorporated via a copolymerization strategy. In a second one, primary amino and imidazole groups are incorporated also via a copolymerization strategy. In a third one, secondary amino groups are substituted with methylguanidine functions through a postpolymerization reaction. Thus, novel polymers of various molecular masses are synthesized, characterized, and their interaction with pDNA studied. Then, their transfection efficiency and cytotoxicity are tested in HeLa cells. Two polymethylvinylamine-based copolymers, one containing 20% of imidazole moieties and another one composed of 12% of guanidinyl units allow remarkable transfection efficiency of HeLa, pulmonary (16HBE), skeletal muscle (C2C12), and dendritic (DC2.4) cells. Overall, this work thus identifies new promising DNA carriers and chemical modifications that improve the transfection efficiency while maintaining low degree of cytotoxicity.
Mots-clés : gene delivery, nanoparticles, POLE 4, POLYMERES, polyvinylamine.
B. Ebeling, K. Belal, F. Stoffelbach, P. Woisel, M. Lansalot, et F. D'Agosto, « Polymer Nanospheres with Hydrophobic Surface Groups as Supramolecular Building Blocks Produced by Aqueous PISA », Macromolecular Rapid Communications, p. 1800455, 2018.
Résumé : A robust and straightforward synthesis of waterborne polymer nanospheres bearing the supramolecular association unit dialkoxynapthalene at their surface is presented using polymerization-induced self-assembly (PISA). A RAFT agent bearing this unit is first employed to produce poly(acrylic acid) chains, which are then chain-extended with styrene (S) to spontaneously form the nano-objects via RAFT aqueous emulsion polymerization. The particular challenge posed by the dialkoxynapthalene hydrophobicity can be overcome by the use of PISA and the deprotonation of the poly(acrylic acid). At pH = 7, very homogeneous latexes are obtained. The particle diameters can be tuned from 36 to 105 nm (with a narrow particle size distribution) by varying the molar mass of the PS block. The surface accessibility of the dialkoxynapthalene moieties is demonstrated by complexation with the complementary host cyclobis(paraquat-p-phenylene) (CBPQT4+ · Cl−), highlighting the potential of the nanospheres to act as building blocks for responsive supramolecular structures.
Mots-clés : emulsion polymerization, POLE 4, polymer nanoparticles, POLYMERES, polymerization-induced self-assembly, RAFT polymerization, supramolecular assembly.
Z. Eskandani, T. Le Gall, T. Montier, P. Lehn, F. Montel, L. Auvray, C. Huin, et P. Guégan, « Polynucleotide transport through lipid membrane in the presence of starburst cyclodextrin-based poly(ethylene glycol)s », The European Physical Journal E, vol. 41, nᵒ 11, p. 132, nov. 2018.
Mots-clés : POLE 4, POLYMERES, Polymers: From Adsorption to Translocation - Topical Issue in Memoriam Loïc Auvray (1956-2016).
P. Evenou, J. Rossignol, G. Pembouong, A. Gothland, D. Colesnic, R. Barbeyron, S. Rudiuk, A. - G. Marcelin, M. Ménand, D. Baigl, V. Calvez, L. Bouteiller, et M. Sollogoub, « Bridging β-Cyclodextrin Prevents Self-Inclusion, Promotes Supramolecular Polymerization, and Promotes Cooperative Interaction with Nucleic Acids », Angewandte Chemie International Edition, vol. 57, nᵒ 26, p. 7753-7758, juin 2018.
Résumé : A bridge to assemble: Cyclodextrins bridged with an ammonium linker bearing a hydrophobic substituent can efficiently form supramolecular polymers and avoid the competing self-inclusion and head-to-head processes. Furthermore, the self-assembling cyclodextrin derivative interacts in a highly cooperative manner with DNA, as demonstrated by compaction experiments. It also interacts cooperatively with siRNA and allows its transfection.
Mots-clés : cyclodextrin, GOBS, inclusion complexes, nucleic acids, POLE 3, POLE 4, POLYMERES, supramolecular polymers.
I. Faye, C. Huin, N. Illy, V. Bennevault, et P. Guégan, « β-Cyclodextrin-Based Star Amphiphilic Copolymers: Synthesis, Characterization, and Evaluation as Artificial Channels », Macromolecular Chemistry and Physics, p. 1800308, oct. 2018.
Résumé : Abstract 14-arm amphiphilic star copolymers are synthesized according to different strategies. First, the anionic ring polymerization of 1,2-butylene oxide (BO) initiated by per(2-O-methyl-3,6-di-O-(3-hydroxypropyl))-?-CD (?-CD?OH14) and catalyzed by t-BuP4 in DMF is investigated. Analyses by NMR and SEC show the well-defined structure of the star ?-CD?-PBO14. To obtain a 14-arm poly(butylene oxide-b-ethylene oxide) star, a Huisgen cycloaddition between an α-methoxy-?-azidopoly(ethylene oxide) and the ?-CD?-PBO14,whose end-chains are beforehand alkyne-functionalized, is performed. In parallel, 14-arm star copolymers composed of butylene oxide-b-glycidol arms are successfully synthesized by the anionic polymerization of ethoxyethylglycidyl ether (EEGE) initiated by ?-CD?-PBO14 with t-BuP4. The deprotection of EEGE units is then performed to provide the polyglycidol blocks. These amphiphilic star polymers are evaluated as artificial channels in lipid bilayers. The effect of changing a PEO block by a polyglycidol block on the insertion properties of these artificial channels is discussed.
Mots-clés : amphiphilic star copolymers, anionic polymerization, artificial channels, phosphazene base, POLE 4, POLYMERES, β-cyclodextrin.
S. Han, E. Nicol, F. Niepceron, O. Colombani, S. Pensec, et L. Bouteiller, « Oligo-Urea with No Alkylene Unit Self-Assembles into Rod-Like Objects in Water », Macromolecular Rapid Communications, p. 1800698, 2018.
Résumé : Long and rigid objects formed by self-assembly in water are useful as templates or for their rheological or biological properties. They are usually obtained by combining hydrogen bonding and strong hydrophobic interactions brought by an alkyl or alkylene chain. A simple access to well-defined rod-like assemblies in water is reported based on a penta-urea sticker directly connected to poly(ethylene oxide) side chains. These assemblies are characterized by an average length of several hundreds of nanometers and a monodisperse radius (4.5 nm) resulting from a reduced lateral aggregation of the stickers.
Mots-clés : hydrogen bonds, light scattering, POLE 4, POLYMERES, rod-like nanoparticles, self-assembly.
A. Jagtap, N. Goubet, C. Livache, A. Chu, B. Martinez, C. Gréboval, J. Qu, E. Dandeu, L. Becerra, N. Witkowski, S. Ithurria, F. Mathevet, M. G. Silly, B. Dubertret, et E. Lhuillier, « Short Wave Infrared Devices Based on HgTe Nanocrystals with Air Stable Performances », The Journal of Physical Chemistry C, vol. 122, nᵒ 26, p. 14979-14985, juill. 2018.
Résumé : Colloidal quantum dots (CQDs) are candidates of interest for the design of low cost IR detector, especially in the short wave infrared (SWIR; 0.8–3 μm), where the vicinity of the visible range makes the high cost of available technologies even more striking. HgTe nanocrystals are among the most promising candidates to address SWIR since their spectrum can be tuned all over this range while demonstrating photoconductive properties. However, several main issues have been swept under the rug, which prevents further development of active materials and devices. Here we address two central questions, which are (i) the stability of the device under ambient air condition and (ii) the reduction of dark current. Encapsulation of HgTe CQDs is difficult because of their extreme sensitivity to annealing, we nevertheless demonstrate an efficient encapsulation method based on a combination of O2 and H2O repellant layers leading to stability over >100 days. Finally, we demonstrate that the dark current reduction can be obtained by switching from a photoconductive geometry to a photovoltaic (PV) device, which is fabricated using solution and low temperature based approach. We demonstrate fast photoresponse (>10 kHz) and detectivity enhancement by 1 order of magnitude in the PV configuration at room temperature. These results pave the way for narrow bandgap CQD based cost-effective optoelectronic devices in developing next generation SWIR photonic systems.
Y. U. Lee, E. Garoni, H. Kita, K. Kamada, B. H. Woo, Y. C. Jun, S. M. Chae, H. J. Kim, K. J. Lee, S. Yoon, E. Choi, F. Mathevet, I. Ozerov, J. C. Ribierre, J. W. Wu, et A. D'Aléo, « Strong Nonlinear Optical Response in the Visible Spectral Range with Epsilon-Near-Zero Organic Thin Films », Advanced Optical Materials, vol. 6, nᵒ 14, p. 1701400, juill. 2018.
Résumé : Enhanced Kerr nonlinearities are observed in metamaterials such as conducting oxides and doped inorganic semiconductor thin films showing epsilon-near-zero (ENZ) response in the infrared region. However, to achieve ENZ in the visible, artificial metamaterials with more complex nanostructures have to be specifically designed. Here, using sodium [5,6-dichloro-2-[[5,6-dichloro-1-ethyl-3-(4-sulphobutyl)-benzimidazol-2-ylidene]-propenyl]-1-ethyl-3-(4-sulphobutyl)-benzimidazolium hydroxide] and [2,4-bis[8-hydroxy-1,1,7,7-tetramethyljulolidin-9-yl]squaraine] organic thin films, ENZ responses between 450 and 620 nm are demonstrated. Both nonlinear refractive index and nonlinear absorption coefficient are enhanced by more than two orders of magnitude in the ENZ spectral region. These optical effects in the visible spectral range come from the strongly dispersive permittivity of molecular aggregates resulting from the coupling of excitonic transition dipoles. These findings open the path toward a next generation of high-performance solution-processable organic nonlinear optical materials with ENZ properties that can be tuned by molecular engineering.
Mots-clés : epsilon near zero (ENZ), molecular aggregates, optical Kerr nonlinearity, organic thin film, POLE 4, POLYMERES.
J. Lyskawa, F. Stoffelbach, D. Fournier, et P. Woisel, « La « Blue Box » : Une molécule hôte pour élaborer des matériaux macromoléculaires (multi)stimulables hauts en couleur », L'Actualité Chimique, nᵒ 430-431, p. 30-36, 2018.
I. Marghad, D. H. Kim, X. Tian, F. Mathevet, C. Gosmini, J. - C. Ribierre, et C. Adachi, « Synthesis by a Cost-Effective Method and Electroluminescence of a Novel Efficient Yellowish-Green Thermally Activated Delayed Fluorescent Molecule », ACS Omega, vol. 3, nᵒ 2, p. 2254-2260, févr. 2018.
Résumé : A new thermally activated delayed fluorescent molecule, TRZ 3(Ph-PTZ), containing three phenothiazines as donor units and a 2,4,6-triphenyl-1,3,5-triazine as the acceptor unit was synthesized using a simple cost-effective method based on a cobalt catalyzed cross-coupling. This compound was tested in organic light-emitting diodes and was found to show superior yellowish-green electroluminescence performance with a maximum external quantum efficiency of 17.4% and a maximum luminance value of 7430 cd/m2.
G. Mellot, P. Beaunier, J. - M. Guigner, L. Bouteiller, J. Rieger, et F. Stoffelbach, « Beyond Simple AB Diblock Copolymers: Application of Bifunctional and Trifunctional RAFT Agents to PISA in Water », Macromolecular Rapid Communications, p. 1800315, 2018.
Résumé : The influence of the macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agent architecture on the morphology of the self-assemblies obtained by aqueous RAFT dispersion polymerization in polymerization-induced self-assembly (PISA) is studied by comparing amphiphilic AB diblock, (AB)2 triblock, and triarm star-shaped (AB)3 copolymers, constituted of N,N-dimethylacrylamide (DMAc = A) and diacetone acrylamide (DAAm = B). Symmetrical triarm (AB)3 copolymers could be synthesized for the first time in a PISA process. Spheres and higher order morphologies, such as worms or vesicles, could be obtained for all types of architectures and the parameters that determine their formation have been studied. In particular, we found that the total DPn of the PDMAc and the PDAAm segments, i.e., the same overall molar mass, at the same Mn(PDMAc)/Mn(PDAAm) ratio, rather than the individual length of the arms determined the morphologies for the linear (AB)2 and star shaped (AB)3 copolymers obtained by using the bi- and trifunctional macro-RAFT agents.
Mots-clés : aqueous RAFT dispersion polymerizations, architectures, morphologies, PISA, POLE 4, POLYMERES, triarm star copolymers.
G. Mellot, J. - M. Guigner, L. Bouteiller, F. Stoffelbach, et J. Rieger, « Templated-PISA: Driving Polymerization-Induced Self-Assembly towards the Fibre Morphology », Angewandte Chemie International Edition, nᵒ ja, 2018.
Résumé : Dispersions of block-copolymer fibres in water have many potential applications and can be obtained by polymerization-induced self-assembly (PISA), but only in very restricted experimental conditions. In order to enlarge this experimental window, we introduced a supramolecular moiety, a hydrogen-bonded bis-urea sticker, in the macromolecular reversible addition-fragmentation chain transfer agent to drive the morphology of the nano-objects produced by RAFT-mediated PISA towards the fibre morphology. This novel concept is tested in the synthesis of a series of poly(N,N-dimethylacrylamide)-b-poly(2-methoxyethyl acrylate) (PDMAc-b-PMEA) diblock copolymers prepared by dispersion polymerization in water. The results prove that the introduction of the templating bis-urea stickers into PISA greatly promotes the formation of fibres in a large experimental window.
Mots-clés : block copolymers, hydrogen bonds, Nanoparticles, POLYMERES, self-assembly, supramolecular chemistry.
G. Mellot, J. - M. Guigner, J. Jestin, L. Bouteiller, F. Stoffelbach, et J. Rieger, « Bisurea-Functionalized RAFT Agent: A Straightforward and Versatile Tool toward the Preparation of Supramolecular Cylindrical Nanostructures in Water », Macromolecules, déc. 2018.
Résumé : We report a versatile and simple approach to produce cylindrical micelles by the direct dissolution of polymers in water. The developed strategy relies on a RAFT agent functionalized by a bisurea sticker that allowed to synthesize a series of α-bisurea-functionalized poly(N,N-dimethylacrylamide) (PDMAc), poly(acrylic acid) (PAA), polyacrylamide (PAM), and poly(2-(N,N-dimethylamino)ethyl acrylate) (PDMAEA) with number-average degrees of polymerization (DPn) varying from about 10 to 50. Their spontaneous self-assembly in water was studied by electron microscopy (cryo-TEM), neutron scattering (SANS), and calorimetry (ITC) analyses which showed that long cylindrical micelles are spontaneously formed in water. The crucial role of the bisurea sticker end-groups was established by comparison with the corresponding bisurea-free model polymers that only formed spherical micelles. Finally, we have shown that it is possible to trigger reversibly the assembly/disassembly of the nanofibers by pH changes.
D. R. Nunes, M. Raynal, B. Isare, P. - A. Albouy, et L. Bouteiller, « Organogel formation rationalized by Hansen solubility parameters: improved methodology », Soft Matter, vol. 14, nᵒ 23, p. 4805-4809, juin 2018.
Résumé : An organogel is obtained when a low molar mass compound forms a network of anisotropic fibres in a liquid that is therefore transformed into a macroscopic solid. Various approaches have been proposed to correlate organogel formation and Hansen solubility parameters. These approaches are well adapted to specific experimental datasets but lack universality. A general method to determine the gelation domain from the solubility data of low molecular weight gelators is here reported.
M. Raynal et L. Bouteiller, « Polymères supramoléculaires et catalyse asymétrique - L'Actualité Chimique », L'Actualité Chimique, nᵒ 430-431, p. 37-41, 2018.
Résumé : Dans le but de développer des catalyseurs asymétriques innovants, des sites catalytiques ont été connectés à des polymères supramoléculaires adoptant une configuration hélicoïdale. Les avantages de cette nouvelle classe de catalyseurs sont que leur composition peut être aisément modulée, qu’une quantité minimale de monomères chiraux est utilisée sans diminuer la sélectivité (amplification de chiralité) et que leur sélectivité est contrôlée en temps réel. Toutes ces propriétés, démontrées pour des réactions métallo-catalysées (Rh, Cu), ne sont pas accessibles avec des catalyseurs conventionnels basés sur des liaisons covalentes. L’utilisation de ces catalyseurs supramoléculaires pour la préparation de petites molécules d’intérêt ou de polymères, non accessibles via les méthodes catalytiques conventionnelles, est envisageable.
J. - C. Ribierre, T. Tanaka, L. Zhao, Y. Yokota, S. Matsumoto, D. Hashizume, K. Takaishi, T. Muto, B. Heinrich, S. Méry, F. Mathevet, T. Matsushima, M. Uchiyama, C. Adachi, et T. Aoyama, « Simultaneous Edge-on to Face-on Reorientation and 1D Alignment of Small π-Conjugated Molecules Using Room-Temperature Mechanical Rubbing », Advanced Functional Materials, vol. 28, nᵒ 19, p. 1707038, mai 2018.
Résumé : In this study, room-temperature mechanical rubbing is used to control the 3D orientation of small π-conjugated molecular systems in solution-processed polycrystalline thin films without using any alignment substrate. High absorption dichroic ratio and significant anisotropy in charge carrier mobilities (up to 130) measured in transistor configuration are obtained in rubbed organic films based on the ambipolar quinoidal quaterthiophene (QQT(CN)4). Moreover, a solvent vapor annealing treatment of the rubbed film is found to improve the optical and charge transport anisotropy due to an increased crystallinity. X-ray diffraction and atomic force microscopy measurements demonstrate that rubbing does not only lead to an excellent 1D orientation of the QQT(CN)4 molecules over large areas but also modifies the orientation of the crystals, moving molecules from an edge-on to a face-on configuration. The reasons why a mechanical alignment technique can be used at room temperature for such a polycrystalline film are rationalized, by the plastic characteristics of the QQT(CN)4 layer and the role of the flexible alkyl side chains in the molecular packing. This nearly complete conversion from edge-on to face-on orientation by mechanical treatment in polycrystalline small-molecule-based thin films opens perspectives in terms of fundamental research and practical applications in organic optoelectronics.
Mots-clés : ambipolar organic field-effect transistors, crystalline domain orientation, mechanical rubbing, molecular alignments, POLE 4, POLYMERES, small π-conjugated molecules.
P. Stiernet, M. Dréan, C. Jérôme, P. Midoux, P. Guégan, J. Rieger, et A. Debuigne, « Tailor-Made Poly(vinylamine)s via Thermal or Photochemical Organometallic Mediated Radical Polymerization », in Reversible Deactivation Radical Polymerization: Mechanisms and Synthetic Methodologies, vol. 1284, American Chemical Society, 2018, p. 349-363.
Résumé : Poly(vinylamine) is a highly valuable class of polymer used in several applications. Although free radical polymerization has been extensively exploited for its synthesis, the preparation of poly(vinylamine) with low dispersity and controlled molar mass is barely developed. Recently, a great step was made in this direction via organometallic-mediated radical polymerization (OMRP) of N-vinylacetamides followed by hydrolysis of the pendent amide groups. This chapter summarizes, completes and put in perspective the main accomplishments in the OMRP of acyclic N-vinylamides for the controlled synthesis of both primary and secondary poly(vinylamine)s. Thermal and photochemical initiating systems are compared and the controlled thermally initiated radical polymerization of N-vinylacetamide is reported for the first time. The optimal hydrolysis conditions for producing the poly(vinylamine) derivatives as well as their potential as vectors for gene transfection are also presented.
F. Abbassi, M. Mbarek, D. Kreher, et K. Alimi, « Synthesis and characterization of a copolymer involving PVK and MEH-PPV for organic electronic devices », Journal of Physics and Chemistry of Solids, vol. 103, p. 142-146.
Résumé : A statistic copolymer denoted (PVK)x-(MEH-PPV)y containing poly(N-vinylcarbazole) (PVK) as well as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) building blocks was prepared by chemical oxidative way. Correlations structure-properties of the synthesized copolymer were investigated by using different experimental analyses (IR, XRD, ATG, optical absorption, PL and PLRT) combined with theoretical calculations (DFT). The new copolymer exhibits interesting properties compared to PVK and MEH-PPV homopolymers taken separately. The resulting copolymer has improved thermal stability and it exhibits original optical properties compared to the PVK and MEH-PPV ones as well as its reveled charge transfer process and the continuous donor acceptor existence. All these experimental and theoretical analysis argue the originality of this new material which could then be exploited in optoelectronics.
Mots-clés : A. Polymers, B. Chemical synthesis, C. Ab initio calculations, C. Optical properties, POLE 4, POLYMERES.
ed fibers », Polymer Chemistry.
Résumé : Polymerization-induced self-assembly (PISA) is an efficient approach to synthesize self-assembled core–shell nanofibers in water, made of amphiphilic block copolymers. We demonstrate here for the first time that such anisotropic and high Tg nanofibers can be used as reinforcing fillers for water-based acrylic materials. This strategy opens the way for strong all-organic aqueous coatings.
M. Chenal, C. Véchambre, J. - M. Chenal, L. Chazeau, V. Humblot, L. Bouteiller, C. Creton, et J. Rieger, « Mechanical properties of nanostructured films with an ultralow volume fraction of hard phase », Polymer, vol. 109, p. 187-196.
Résumé : We demonstrate in this paper how polymerization induced self-assembly (PISA) using RAFT can be used to synthesize very asymmetric but monodisperse poly(acrylic acid)-b-poly(n-butyl acrylate) block copolymers, PAA-b-PBA, with a short PAA block and a long PBA block. In the course of the surfactant-free emulsion polymerization, core-shell particles form in water, with the short hydrophilic block located at the water-particle interface, and the long hydrophobic block constituting the particle core. Drying at room temperature creates films possessing an out of equilibrium structure, where the glassy PAA block generates a percolating network of shells. When deformed in uniaxial elongation, these films combine a high stiffness in small strains (considering the low volume fraction of PAA, of only 3 wt%), a yield stress and a significant extensibility before failure. The modulus, yield stress and extensibility can be tuned by modifying the composition of the latex serum with cations or positively charged low molar mass polymers, or by changing the copolymer composition. Of particular interest was the synthesis by PISA of particles of triblock copolymer PAA-b-PBA-b-PS. The out of equilibrium structure obtained had a very interesting combination of high stiffness, extensibility and high fracture toughness.
Mots-clés : Core-shell latexes, Film, Mechanical properties, Nanostructure, POLE 4, POLYMERES, RAFT polymerization.
M. Dréan, A. Debuigne, C. Goncalves, C. Jérôme, P. Midoux, J. Rieger, et P. Guégan, « Use of Primary and Secondary Polyvinylamines for Efficient Gene Transfection », Biomacromolecules, vol. 18, nᵒ 2, p. 440-451.
Résumé : 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 of 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.
M. Fumagalli, K. Belal, H. Guo, F. Stoffelbach, G. Cooke, A. Marcellan, P. Woisel, et D. Hourdet, « Supramolecular polymer hydrogels induced by host–guest interactions with di-[cyclobis(paraquat-p-phenylene)] cross-linkers: from molecular complexation to viscoelastic properties », Soft Matter, vol. 13, nᵒ 31, p. 5269-5282.
Résumé : Supramolecular polymer networks have been designed on the basis of a π-electron donor/acceptor complex: naphthalene (N)/cyclobis(paraquat-p-phenylene) (CBPQT4+ = B). For this purpose, a copolymer of N,N-dimethylacrylamide P(DMA-N1), lightly decorated with 1 mol% of naphthalene pendant groups, has been studied in semi-dilute un-entangled solution in the presence of di-CBPQT4+ (BB) crosslinker type molecules. While calorimetric experiments demonstrate the quantitative binding between N and B groups up to 60 °C, the introduction of BB crosslinkers into the polymer solution gives rise to gel formation above the overlap concentration. From a comprehensive investigation of viscoelastic properties, performed at different concentrations, host/guest stoichiometric ratios and temperatures, the supramolecular hydrogels are shown to follow a Maxwellian behavior with a strong correlation of the plateau modulus and the relaxation time with the effective amount of interchain cross-linkers and their dissociation dynamics, respectively. The calculation of the dissociation rate constant of the supramolecular complex, by extrapolation of the relaxation time of the network back to the beginning of the gel regime, is discussed in the framework of theoretical and experimental works on associating polymers.
C. Gonçalves, J. - P. Gomez, W. Même, B. Rasolonjatovo, D. Gosset, S. Nedellec, P. Hulin, C. Huin, T. Le Gall, T. Montier, P. Lehn, C. Pichon, P. Guégan, H. Cheradame, et P. Midoux, « Curcumin/poly(2-methyl-2-oxazoline-b-tetrahydrofuran-b-2-methyl-2-oxazoline) formulation: An improved penetration and biological effect of curcumin in F508del-CFTR cell lines », European Journal of Pharmaceutics and Biopharmaceutics, vol. 117, p. 168-181.
Résumé : Neutral amphiphilic triblock ABA copolymers are of great interest to solubilize hydrophobic drugs. We reported that a triblock ABA copolymer consisting of methyl-2-oxazoline (MeOx) and tetrahydrofuran (THF) (MeOx6-THF19-MeOx6) (TBCP2) can solubilize curcumin (Cur) a very hydrophobic molecule exhibiting multiple therapeutic effects but whose insolubility and low stability in water is a major drawback for clinical applications. Here, we provide evidences by flow cytometry and confocal microscopy that Cur penetration in normal and ΔF508-CFTR human airway epithelial cell lines is facilitated by TBCP2. When used on ΔF508-CFTR cell lines, the Cur/TBCP2 formulation promotes the restoration of the expression of the CFTR protein in the plasma membrane. Furthermore, patch-clamp and MQAE fluorescence experiments show that this effect is associated with a correction of a Cl− selective current at the membrane surface of F508del-CFTR cells. The results show the great potential of the neutral amphiphilic triblock copolymer MeOx6-THF19-MeOx6 as carrier for curcumin in a Cystic Fibrosis context. We anticipate that other MeOxn-THFm-MeOxn copolymers could have similar behaviours for other highly insoluble therapeutic drugs or cosmetic active ingredients.
Mots-clés : Amphiphilic polymer, CFTR, Curcumin, Cystic fibrosis, POLE 4, POLYMERES, Triblock copolymer.
L. Hassouna, N. Illy, et P. Guégan, « Phosphazene/triisobutylaluminum-promoted anionic ring-opening polymerization of 1,2-epoxybutane initiated by secondary carbamates », Polymer Chemistry, vol. 8, nᵒ 27, p. 4005-4013.
Résumé : Attempts to use a carbamate-phosphazene base as the initiating system for the polymerization of 1,2-epoxybutane was unsuccessful. As a matter of fact, carbamate deprotonation by phosphazene bases led to their fast decomposition generating alkoxide anions which initiate the polymerization rather than carbamate anions. Conversely, in the presence of triisobutylaluminum – a Lewis acid – the in situ generation of an anionic initiator X− obtained by the deprotonation of the tBuP4 phosphazene base was tested as a possible way to initiate the polymerization of 1,2-epoxybutane. Particular attention was given to the detection of eventual transfer or side-reactions according to the carbamate:triisobutylaluminum:phosphazene base ratio, to the solvent dielectric constant and to the number of PN– units in the phosphazene base. The reaction was performed with a stoichiometric ratio (1:1:1) of carbamate:triisobutylaluminum:tBuP2, which gave the best results. Under these conditions, the initiation of the polymerization by the carbamate anion was quantitative; no transfer reactions have been observed and the polymerization proceeded in a controlled manner to afford amide end-capped poly(butylene oxide) with a narrow molar mass distribution and expected molar masses.
K. J. Lee, Y. Xiao, J. H. Woo, E. Kim, D. Kreher, A. - J. Attias, F. Mathevet, J. - C. Ribierre, J. W. Wu, et P. André, « Charge-transfer dynamics and nonlocal dielectric permittivity tuned with metamaterial structures as solvent analogues », Nature Materials, vol. advance online publication, juin 2017.
Résumé : Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene:perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7—that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal–dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.
Mots-clés : Metamaterials, POLE 4, POLYMERES, Structural properties, Ultrafast photonics.
A. Pontes da Costa, D. R. Nunes, M. Tharaud, J. Oble, G. Poli, et J. Rieger, « Palladium(0) Nanoparticles Embedded in Core–shell Nanogels as Recoverable Catalysts for the Mizoroki–Heck Reaction », ChemCatChem, vol. 9, nᵒ 12, p. 2167-2175, juin 2017.
Résumé : Core–shell nanogels are attractive stabilizers and supports for catalytically active metallic nanoparticles. Herein, we present the synthesis and the characterization of a nanostructured well-defined core–shell nanogel with the ability to stabilize Pd0 nanoparticles in its core. This hybrid nanogel displays a remarkable stability in both the solid state and in solution. This feature allowed its successful application as a catalyst for the Mizoroki–Heck reaction between n-butyl acrylate and a series of bromo- and iodoarenes. The yields spanned from good to excellent, and catalyst recycling could be achieved up to three times without a significant activity loss. Three-phase tests indicated that the hybrid nanogel acts as a Pd0 nanoreservoir. The catalysis proceeds in a quasihomogeneous fashion as part of the catalytic activity occurs outside the nanogel, which explains the observed limited recyclability.
Mots-clés : C−C coupling, immobilization, Palladium, POLE 1, POLE 4, POLYMERES, RAFT polymerization, ROCS, supported catalysts.
A. Six, A. Bocheux, F. Charra, F. Mathevet, D. Kreher, et A. - J. Attias, « 2D self-assembly of phenylene–vinylene tectons at the liquid–highly oriented pyrolytic graphite interface: from chain length effects to anisotropic guest–host dynamics », Nanotechnology, vol. 28, nᵒ 2, p. 025602.
Résumé : Here we report the synthesis and characterization of a series of new phenylene–vinylene tectons. The study by scanning tunneling microscopy of their supramolecular self-assembly at the interface between a phenyloctane solution and highly oriented pyrolyticgraphite demonstrates that variation of concentration and length of alkyl chains led to the formation of different networks, a compact one and a nanoporous one, with a fine control of the lattice parameters. The study of guest–host properties of the nanoporous network revealed a selectivity toward guest compounds according to their shape and size. Moreover, the statistical analysis of pore-to-pore guest dynamics evidences an anisotropic diffusion process.
L. Sosa-Vargas, E. Kim, et A. - J. Attias, « Beyond “decorative” 2D supramolecular self-assembly: strategies towards functional surfaces for nanotechnology », Materials Horizons.
Résumé : 2D supramolecular self-assembly has emerged as a powerful tool in nanoscience for bottom-up fabrication of well-defined and long-range ordered two-dimensional (2D) molecular nanostructures at surfaces. Following an overview of the principles of this distinctive self-assembly process, this review focuses on recent strategies developed to go beyond surface nanopatterning and to provide functional surfaces. With an emphasis on the chemical engineering of the molecular building blocks constituting the adlayer, we show that besides supported nanoporous networks, a more promising approach lies in the upstanding 3D functional building blocks mounted on the substrate. We highlight the opportunities offered by graphene, a substrate for which non-covalent functionalization by supramolecular self-assembly represents a way to either control its electronic properties or provide a new functionality. Finally, future perspectives are addressed.
R. Triki, A. Bougarech, M. Tessier, S. Abid, A. Fradet, et M. Abid, « Furanic–Aliphatic Polyesteramides by Bulk Polycondensation Between Furan-Based Diamine, Aliphatic Diester and Diol », Journal of Polymers and the Environment, p. 1-7.
Résumé : In order to prepare furanic–aliphatic polyesteramides without the side reactions taking place with furan-2-carboxylic acids or esters, a furan-based diamine, 5,5′-isopropylidenebis(2-furfurylamine), was reacted in the bulk, either with (i) ethanediol and dimethyl adipate or (ii) with the corresponding aliphatic polyester (polyethylene adipate). The polycondensation involves both amine–ester and hydroxy–ester interchanges, with elimination of excess ethanediol. High-molar-mass furanic–aliphatic polyesteramides were easily obtained. Method (ii) was more efficient than method (i), but no side reactions were observed with both methods. These polyesteramides behave as amorphous random copolymers.
Y. Xiao, D. Zeng, L. M. Mazur, A. Castiglione, E. Lacaze, B. Heinrich, B. Donnio, D. Kreher, A. - J. Attias, J. - C. Ribierre, et F. Mathevet, « A new class of nanostructured supramolecular organic semiconductors based on intertwined multi-lamellar co-assemblies in π-conjugated liquid-crystalline side-chain polymers », Polymer Journal, vol. 49, nᵒ 1, p. 31-39.
Résumé : The control of both the mesoscopic and nanoscale organizations within thin semiconducting films is a key issue for the improvement of the charge transport properties and the achievement of high charge-carrier mobilities. In this review, we summarized our previous work devoted to the design and synthesis of a new type of side-chain liquid crystal π-conjugated polymeric system associating regioregular poly(3-alkylthiophene) backbones with laterally pending π-conjugated mesogenic groups. Depending on the nature of the mesogenic side groups, this specific polymer design permits the production of lamellocolumnar or lamellolamellar mesophases, resulting in an intertwined co-assembly either of lamellae and columns or of two different types of lamellae. These optimized polymeric architectures based on two chemically different moieties constitute an interesting basis for the design of novel self-organized complex semiconducting materials. By associating with judicious side groups such as n-type entities, we demonstrated that this simple and versatile strategy can produce distinct conductive channels for both types of charge carrier and can lead to a new class of supramolecular ambipolar materials that is easily processable and potentially suitable for electronic and optoelectronic applications.
A. Ali Mohamed, S. Salhi, S. Abid, R. El Gharbi, et A. Fradet, « Quasi-alternating polyesteramides from ε-caprolactone and α-amino acids », Journal of Applied Polymer Science, vol. 133, nᵒ 46, p. n/a-n/a.
Résumé : Glycine-ɛ-caprolactone-based and α-alanine-ɛ-caprolactone-based polyesteramides with a strong tendency to form alternating sequences (degree of randomness = 1.64 and 1.31) were synthesized by melt polycondensation of intermediate hydroxy- and ethyl ester-terminated amides. These intermediates were synthesized by the reaction of equimolar amounts of ɛ-caprolactone and glycine or L-α-alanine ethyl esters in mild conditions. The structure and microstructure of these polyesteramides are discussed on the basis of an in-depth nuclear magnetic resonance study. Both polyesteramides are semi-crystalline, but the glycine-based one presents the highest melting enthalpy. This polyesteramide also exhibits higher Young's modulus and stress at break than its α- and β-alanine counterparts. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44220.
Mots-clés : biopolymers and renewable polymers, POLE 4, Polyesteramides, polyesters, POLYMERES, α-amino acids.
V. Ayzac, L. Bouteiller, M. Raynal, et B. Isare, « Thermo-thickening compounds for non-polar liquid », U.S. Patent EP 16203527.
S. Poitras-Jolicoeur, J. Lyskawa, G. Pembouong, G. Cooke, P. Woisel, et F. Stoffelbach, « A triple carboxylic acid-functionalized RAFT agent platform for the elaboration of well-defined telechelic 3-arm star PDMAc », Chemical Communications, vol. 52, nᵒ 9, p. 1847-1850, janv. 2016.
Résumé : This communication describes the synthesis of a triple acid-functionalized RAFT agent and its use to prepare well-defined 3-arm star polymers of N,N-dimethylacrylamide (DMAc). A simple esterification reaction allowed the convenient integration of three electron-rich naphthalene recognition units on the RAFT agent platform and subsequently the elaboration of a naphthalene end-decorated telechelic 3-arm star PDMAc. This functionalized star polymer was further exploited to build a hydrogel with a complementary homoditopic host unit featuring tetracationic macrocycle cyclobis(paraquat-p-phenylene) units.
K. Belal, F. Stoffelbach, J. Lyskawa, M. Fumagalli, D. Hourdet, A. Marcellan, L. De Smet, V. R. de la Rosa, G. Cooke, R. Hoogenboom, et P. Woisel, « Recognition-mediated hydrogel swelling controlled by interaction with a negative thermoresponsive LCST polymer », Angewandte Chemie International Edition, vol. 55, nᵒ 45, p. 13974-13978.
Résumé : Most polymeric thermoresponsive hydrogels contract upon heating beyond the lower critical solution temperature (LCST) of the polymers used. Herein, we report a supramolecular hydrogel system that shows the opposite temperature dependence. When the non-thermosesponsive hydrogel NaphtGel, containing dialkoxynaphthalene guest molecules, becomes complexed with the tetra cationic macrocyclic host CBPQT4+, swelling occurred as a result of host–guest complex formation leading to charge repulsion between the host units, as well as an osmotic contribution of chloride counter-ions embedded in the network. The immersion of NaphtGel in a solution of poly(N-isopropylacrylamide) with tetrathiafulvalene (TTF) end groups complexed with CBPQT4+ induced positive thermoresponsive behaviour. The LCST-induced dethreading of the polymer-based pseudorotaxane upon heating led to transfer of the CBPQT4+ host and a concomitant swelling of NaphtGel. Subsequent cooling led to reformation of the TTF-based host–guest complexes in solution and contraction of the hydrogel.
C. Ben Osman, R. Geagea, et F. Stoffelbach, « Synthesis of a new donor-acceptor-donor functionalized alkoxyamine and its use in a reversibly supported catalytic hybrid system for ATRP of MMA », Polymer, vol. 99, p. 654-661.
Résumé : A new 2,6-diaminopyridine-functionalized SG1-based alkoxyamine has been synthesized and used to prepare a well-defined functional copolymer (poly(styrene-co-2-vinyl-4,4-dimethyl-5-oxazolone) – poly(S-co-VDM)) by nitroxide mediated polymerization. After post-modification of the copolymer with an atom transfer radical polymerization (ATRP) ligand (N,N-dipicolyl propylamine), the macroligand was successfully used for the homogeneous ATRP of methyl methacrylate (MMA) leading to a controlled polymerization process. The ATRP of the same monomer was also investigated with the macroligand being reversibly immobilized via hydrogen bonding onto thymine-functionalized silica nanoparticles. The ATRP of MMA involving the supported-catalyst was also effective leading to a good control over the polymerization as observed with the free macroligand and producing polymers with very low dispersity (&lt;1.2). After separation of the supported catalyst by centrifugation, the amount of residual catalyst in the resulting polymers was determined.
Mots-clés : ATRP, Hydrogen bonding, Macroligand, Picolyl amine, POLE 4, POLYMERES, Silica nanoparticle, supported catalyst.
V. Besse, N. Illy, G. David, S. Caillol, et B. Boutevin, « A Chitosan Derivative Containing Both Carboxylic Acid and Quaternary Ammonium Moieties for the Synthesis of Cyclic Carbonates », ChemSusChem, vol. 9, nᵒ 16, p. 2167-2173, 2016.
Résumé : Chitosan, a renewable feedstock, is modified and used as a catalytic support in the presence of potassium iodide. The system is highly efficient towards the incorporation of carbon dioxide (CO2) into epoxides. It demonstrates very good thermal stability and is recyclable more than five times without loss of activity. The optimal reaction conditions were determined using allylglycidyl ether as a model and extended to a wide range of other epoxides. Cyclic carbonates were obtained with very high yield in a few hours under mild conditions (2–7 bar≈0.2–0.7 MPa, 80 °C) and no solvent.
Mots-clés : chitosan, cyclic carbonates, epoxides, heterogeneous catalysis, POLE 4, POLYMERES, supported catalyst.
X. Callies, C. Fonteneau, S. Pensec, L. Bouteiller, G. Ducouret, et C. Creton, « Adhesion and non-linear rheology of adhesives with supramolecular crosslinking points », Soft Matter, vol. 12, nᵒ 34, p. 7174-7185.
Résumé : Soft supramolecular materials are promising for the design of innovative and highly tunable adhesives. These materials are composed of polymer chains functionalized by strongly interacting moieties, sometimes called “stickers”. In order to systematically investigate the effect of the presence of associative groups on the debonding properties of a supramolecular adhesive, a series of supramolecular model systems has been characterized by probe-tack tests. These model materials, composed of linear and low dispersity poly(butylacrylate) chains functionalized in the middle by a single tri-urea sticker, are able to self-associate by six hydrogen bonds and range in molecular weight (Mn) between 5 and 85 kg mol−1. The linear rheology and the nanostructure of the same materials (called “PnBA3U”) were the object of a previous study. At room temperature, the association of polymers via hydrogen bonds induces the formation of rod-like aggregates structured into bundles for Mn &lt; 40 kg mol−1 and the behavior of a soft elastic material was observed (G′ ≪ G′′ and G′ ∼ ω0). For higher Mn materials, the filaments were randomly oriented and the polymers displayed a crossover towards viscous behavior although terminal relaxation was not reached in the experimental frequency window. All these materials show, however, similar adhesive properties characterized by a cohesive mode of failure and low debonding energies (Wadh &lt; 40 J m−2 for a debonding speed of 100 μm s−1). The debonding mechanisms observed during the adhesion tests have been investigated in detail with an Image tools analysis developed by our group. The measure of the projected area covered by cavities growing in the adhesive layer during debonding can be used to estimate the true stress in the walls of the cavities and thus to characterize the in situ large strain deformation of the thin layer during the adhesion test itself. This analysis revealed in particular that the PnBA3U materials with Mn &lt; 40 kg mol−1 soften very markedly at large deformation like yield stress fluids, explaining the low adhesion energies measured for these viscoelastic gels.
X. Callies, O. Herscher, C. Fonteneau, A. Robert, S. Pensec, L. Bouteiller, G. Ducouret, et C. Creton, « Combined Effect of Chain Extension and Supramolecular Interactions on Rheological and Adhesive Properties of Acrylic Pressure-Sensitive Adhesives », ACS Applied Materials & Interfaces, vol. 8, nᵒ 48, p. 33307-33315.
Résumé : A new approach for the elaboration of low molecular weight pressure-sensitive adhesives based on supramolecular chemistry is explored. The synthesis of model systems coupled with probe-tack tests and rheological experiments highlights the influence of the transient network formed by supramolecular bonds on the adhesion energy. The first step of our approach consists of synthesizing poly(butyl acrylate-co-glycidyl methacrylate) copolymers from a difunctional initiator able to self-associate by four hydrogen bonds between urea groups. Linear copolymers with a low dispersity (Mn = 10 kg/mol, Ip < 1.4) have been synthesized via atom transfer radical polymerization. Films of the copolymers were then partially cross-linked through reaction of the epoxy functions with a diamine. The systematic variation of the average ratio of glycidyl methacrylate and diamine per copolymer shed light on the respective role played by the supramolecular interactions (between bis-urea groups and with the side chains) and by the chain extension and branching induced by the diamine/epoxy reaction. In this strategy, the adhesive performance can be optimized by modifying the strength of “stickers” (via the structure of the supramolecular initiator, for instance) and the polymer network (e.g., via the length and level of branching of the copolymer chains) in order to approach commercial PSA-like properties (high debonding energy and clean removal).
V. Calvez, A. G. Marcellin, L. Bouteiller, M. Menand, P. Evenou, A. Gothland, D. Colesnic, J. Rossignol, et M. Sollogoub, « Capped cyclodextrin-hydrophobic moiety conjugate, cyclodextrin supramolecular polymer, and cyclodextrin-siRNA complex and method of synthesis thereof », U.S. Patent PCT/ EP2016/070892.
Mots-clés : GOBS, POLE 3, POLE 4, POLYMERES.
S. Catrouillet, L. Bouteiller, O. Boyron, C. Lorthioir, E. Nicol, S. Pensec, et O. Colombani, « Patchy Supramolecular Bottle-Brushes Formed by Solution Self-Assembly of Bis(urea)s and Tris(urea)s Decorated by Two Incompatible Polymer Arms », Langmuir, vol. 32, nᵒ 35, p. 8900-8908.
Résumé : In an attempt to design urea-based Janus nanocylinders through a supramolecular approach, nonsymmetrical bis(urea)s and tris(urea)s decorated by two incompatible polymer arms, namely, poly(styrene) (PS) and poly(isobutylene) (PIB), were synthesized using rather straightforward organic and polymer chemistry techniques. Light scattering experiments revealed that these molecules self-assembled in cyclohexane by cooperative hydrogen bonds. The extent of self-assembly was limited for the bis(urea)s. On the contrary, reasonably anisotropic 1D structures (small nanocylinders) could be obtained with the tris(urea)s (Nagg ∼ 50) which developed six cooperative hydrogen bonds per molecule. 1H transverse relaxation measurements and NOESY NMR experiments in cyclohexane revealed that perfect Janus nanocylinders with one face consisting of only PS and the other of PIB were not obtained. Nevertheless, phase segregation between the PS and PIB chains occurred to a large extent, resulting in patchy cylinders containing well separated domains of PIB and PS chains. Reasons for this behavior were proposed, paving the way to improve the proposed strategy toward true urea-based supramolecular Janus nanocylinders.
X. Caumes, A. Baldi, G. Gontard, P. Brocorens, R. Lazzaroni, N. Vanthuyne, C. Troufflard, M. Raynal, et L. Bouteiller, « Tuning the structure of 1,3,5-benzene tricarboxamide self-assemblies through stereochemistry », Chemical Communications, vol. 52, nᵒ 91, p. 13369-13372, nov. 2016.
Résumé : A heterochiral 1,3,5-benzene tricarboxamide (BTA) monomer, derived from valine dodecyl ester, forms long rods in cyclohexane whilst its homochiral analogue assembles into dimers only at the same concentration. This highly original assembly behaviour is related to the destabilization of the dimeric structure containing the two heterochiral monomers as corroborated by a combined experimental and computational study.
M. C. Chong, G. Reecht, H. Bulou, A. Boeglin, F. Scheurer, F. Mathevet, et G. Schull, « Narrow-Line Single-Molecule Transducer between Electronic Circuits and Surface Plasmons », Physical Review Letters, vol. 116, nᵒ 3, p. 036802.
Résumé : A molecular wire containing an emitting molecular center is controllably suspended between the plasmonic electrodes of a cryogenic scanning tunneling microscope. Passing current through this circuit generates an ultranarrow-line emission at an energy of ≈1.5 eV which is assigned to the fluorescence of the molecular center. Control over the linewidth is obtained by progressively detaching the emitting unit from the surface. The recorded spectra also reveal several vibronic peaks of low intensities that can be viewed as a fingerprint of the emitter. Surface plasmons localized at the tip-sample interface are shown to play a major role in both excitation and emission of the molecular excitons.
M. C. Chong, L. Sosa-Vargas, H. Bulou, A. Boeglin, F. Scheurer, F. Mathevet, et G. Schull, « Ordinary and Hot Electroluminescence from Single-Molecule Devices: Controlling the Emission Color by Chemical Engineering », Nano Letters, vol. 16, nᵒ 10, p. 6480-6484.
Résumé : Single-molecule junctions specifically designed for their optical properties are operated as light-emitting devices using a cryogenic scanning tunneling microscope. They are composed of an emitting unit—a molecular chromophore—suspended between a Au(111) surface and the tip of the microscope by organic linkers. Tunneling electrons flowing through these junctions generate a narrow-line emission of light whose color is controlled by carefully selecting the chemical structure of the emitting unit. Besides the main emission line, red and blue-shifted vibronic features of low intensity are also detected. While the red-shifted features provide a spectroscopic fingerprint of the emitting unit, the blue-shifted ones are interpreted in terms of hot luminescence from vibrationally excited states of the molecule.
A. Debuigne, M. Dréan, P. Guégan, C. Jérôme, P. Midoux, et J. Rieger, « Improvements in or Relating to Organic Material », U.S. Patent EP16165764.
A. Desmarchelier, B. G. Alvarenga, X. Caumes, L. Dubreucq, C. Troufflard, M. Tessier, N. Vanthuyne, J. Idé, T. Maistriaux, D. Beljonne, P. Brocorens, R. Lazzaroni, M. Raynal, et L. Bouteiller, « Tuning the nature and stability of self-assemblies formed by ester benzene 1,3,5-tricarboxamides: the crucial role played by the substituents », Soft Matter, vol. 12, nᵒ 37, p. 7824-7838.
Résumé : As the benzene 1,3,5-tricarboxamide (BTA) moiety is commonly used as the central assembling unit for the construction of functionalized supramolecular architectures, strategies to tailor the nature and stability of BTA assemblies are needed. The assembly properties of a library of structurally simple BTAs derived from amino dodecyl esters (ester BTAs, 13 members) have been studied, either in the bulk or in cyclohexane solutions, by means of a series of analytical methods (NMR, DSC, POM, FT-IR, UV-Vis, CD, ITC, high-sensitivity DSC, SANS). Two types of hydrogen-bonded species have been identified and characterized: the expected amide-bonded helical rods (or stacks) that are structurally similar to those formed by BTAs with simple alkyl side chains (alkyl BTAs), and ester-bonded dimers in which the BTAs are connected by means of hydrogen bonds linking the amide N–H and the ester CO. MM/MD calculations coupled with simulations of CD spectra allow for the precise determination of the molecular arrangement and of the hydrogen bond pattern of these dimers. Our study points out the crucial influence of the substituent attached on the amino-ester α-carbon on the relative stability of the rod-like versus dimeric assemblies. By varying this substituent, one can precisely tune the nature of the dominant hydrogen-bonded species (stacks or dimers) in the neat compounds and in cyclohexane over a wide range of temperatures and concentrations. In the neat BTAs, stacks are stable up to 213 °C and dimers above 180 °C whilst in cyclohexane stacks form at c* &gt; 3 × 10−5 M at 20 °C and dimers are stable up to 80 °C at 7 × 10−6 M. Ester BTAs that assemble into stacks form a liquid-crystalline phase and yield gels or viscous solutions in cyclohexane, demonstrating the importance of controlling the structure of these assemblies. Our systematic study of these structurally similar ester BTAs also allows for a better understanding of how a single atom or moiety can impact the nature and stability of BTA aggregates, which is of importance for the future development of functionalized BTA supramolecular polymers.
A. Desmarchelier, X. Caumes, M. Raynal, A. Vidal-Ferran, P. W. N. M. van Leeuwen, et L. Bouteiller, « Correlation between the Selectivity and the Structure of an Asymmetric Catalyst Built on a Chirally Amplified Supramolecular Helical Scaffold », Journal of the American Chemical Society, vol. 138, nᵒ 14, p. 4908-4916.
Résumé : For the first time, supramolecular helical rods composed of an achiral metal complex and a complementary enantiopure monomer provided a good level of enantioinduction in asymmetric catalysis. Mixtures containing an achiral ligand monomer (BTAPPh2, 2 mol %) and an enantiopure ligand-free comonomer (ester BTA, 2.5 mol %), both possessing a complementary benzene-1,3,5-tricarboxamide (BTA) central unit, were investigated in combination with [Rh(cod)2]BArF (1 mol %) in the asymmetric hydrogenation of dimethyl itaconate. Notably, efficient chirality transfer occurs within the hydrogen-bonded coassemblies formed by BTA Ile and the intrinsically achiral catalytic rhodium catalyst, providing the hydrogenation product with up to 85% ee. The effect of the relative content of BTA Ile as compared to the ligand was investigated. The amount of chiral comonomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction, while the enantioselectivity decreases for mixtures containing high amounts of BTA Ile. The nonlinear relationship between the amount of chiral comonomer and the enantioselectivity indicates that chirality amplification effects are at work in this catalytic system. Also, right-handed helical rods are formed upon co-assembly of the achiral rhodium complex of BTAPPh2 and the enantiopure comonomer BTA Ile as confirmed by various spectroscopic and scattering techniques. Remarkably, the major enantiomer and the selectivity of the catalytic reaction are related to the handedness and the net helicity of the coassemblies, respectively. Further development of this class of catalysts built on chirally amplified helical scaffolds should contribute to the design of asymmetric catalysts operating with low amounts of chiral entities.
M. Dréan, P. Guégan, C. Detrembleur, C. Jérôme, J. Rieger, et A. Debuigne, « Controlled Synthesis of Poly(vinylamine)-Based Copolymers by Organometallic-Mediated Radical Polymerization », Macromolecules, vol. 49, nᵒ 13, p. 4817-4827.
Résumé : Living/controlled polymerization methods have enabled the synthesis of numerous (co)polymers with defined compositions and architectures. However, the precision design of poly(vinylamine)-based copolymers remains challenging despite their extensive use in various fields of applications and the clear benefits to finely tune their properties. Here, we report on a two-step strategy for the synthesis of tailor-made poly(vinylamine) derivatives through the organometallic-mediated radical (co)polymerization (OMRP) of N-vinylacetamide and/or N-methylvinylacetamide followed by acid hydrolysis of the acetamide groups. A series of well-defined homopolymers as well as statistical and block copolymers with pendant primary and/or secondary amines having controlled molar masses, compositions, and low dispersities were produced accordingly. The reactivity ratios of the comonomers as well as the composition drift along the chain were determined in order to have a precise idea of the polymer structures. These advances represent a significant step toward an efficient platform for synthesis of this important class of amino group-containing (co)polymers.

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