Contribution à l'étude et à la modélisation de la mésostructure de composites polymères-noir de carbone

Les propriétés physiques des matériaux hétérogènes polymère/noir de carbone sont étroitement liées à l'arrangement des particules conductrices dans la matrice, c'est-à-dire à leur mésostructure. Afin d'étudier celle-ci, nous avons utilisé une extension de la microscopie à champ proche appel ée Résiscope qui permet grâce aux propriétés électriques locales de ces matériaux de révéler les connexions électriques entre particules. L'analyse comparative de trois séries de matériaux ayant subi des mélangeages différents a permis de montrer qu'un modèle de percolation ne représente que très imparfaitement la mésostructure des matériaux réels et qu'une analyse numérique appropriée des images fournit des renseignements sur la mésostructure à courte et à grande échelles. Enfin, nous avons entrepris l'élaboration de modèles de structures alternatifs fondés sur des données de microscopie électronique en transmission.The physical properties of heterogeneous materials, polymer/carbon black composites, depend closely on the arrangement of the particles in the matrix which is called the mesostructure. In order to study it, we have used an extension of the AFM microscope that takes advantage of the local electrical properties of the materials for characterizing the electrical connections among particles. The comparative study of three series of samples processed with different mixing conditions allowed us to show that percolation models do not represent adequately the actual mesostructure. Besides, appropriate numerical analysis of the images allowed us to deduce distinct information on the mesostructure at short and long scales. In a last part, we have initiated the construction of new mathematical models for the mesostructure based on transmission electronic micrographs of the materials

Loading linear arrays of Cu(II) inside aromatic amide helices

The very stable helices of 8-amino-2-quinolinecar-boxylic acid oligoamides are shown to uptake CuIIions in theircavity through deprotonation of their amide functions with minimal alteration of their shape, unlike most metallo-organicstructures which generally differ from their organic precursors.The outcome is the formation of intramolecular linear arrays of a defined number of CuIIcenters (up to sixteen in this study)at a 3 distance, forming a molecular mimic of a metal wirecompletely surrounded by an organic sheath. The helices packin the solid state so that the arrays of CuIIextend intermolecularly. Conductive-AFM and cyclic voltammetry suggest thatelectrons are transported throughout the metal-loaded helices in contrast with hole transport observed for analogous foldamers devoid of metal ions.Les voies de signalisation du récepteur 5-HT6: de nouvelles cibles pour le traitement de la douleur neuropathique

Contribution à l'étude et à la modélisation de la mésostructure de composites polymères-noir de carbone

Les propriétés physiques des matériaux hétérogènes polymère/noir de carbone sont étroitement liées à l'arrangement des particules conductrices dans la matrice, c'est-à-dire à leur mésostructure. Afin d'étudier celle-ci, nous avons utilisé une extension de la microscopie à champ proche appelée Résiscope qui permet grâce aux propriétés électriques locales de ces matériaux de révéler les connexions électriques entre particules. L'analyse comparative de trois séries de matériaux ayant subi des mélangeages différents a permis de montrer qu'un modèle de percolation ne représente que très imparfaitement la mésostructure des matériaux réels et qu'ne analyse numérique appropriée des images fournit des renseignements sur la mésostructure à courte et à grande échelles. Enfin, nous avons entrepris l'élaboration de modèles de structures alternatifs fondés sur des données de microscopie électronique en transmission.BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Non-destructive depth-dependent morphological characterization of ferroelectric:semiconducting polymer blend films

Herein we investigate the technologically relevant blend of the ferroelectric polymer poly(vinylidene fluorideco-trifluoroethylene), P(VDF-co-TrFE), with the semiconducting polymer poly(3-hexylthiophene), P3HT, by means of a combination of Scanning Probe Microscopy techniques, namely Atomic Force Microscopy, Conductive Force Microscopy, Kelvin Probe Force Microscopy and Piezoresponse Force Microscopy. This combination proves to be a powerful tool for the non-destructive morphological reconstruction of multifunctional nano-structured thin films, as those under study. Each modality allows discerning the two blend constituents based on their functionality, and, additionally, probes layers of different thickness with respect to the films surface. The depth-dependent information that is collected allows a qualitative reconstruction of the blend's composition and morphology both in-plane and out-of-plane of the film. We demonstrate that P3HT exhibits the tendency to reside the film surface at an almost constant composition of 15%, independent of blend's composition. Increasing the P3HT content in the blend results in the segregation of P3HT at the upper layers of the films, partially buried below a P(VDF-co-TrFE) superficial layer. The depletion of P3HT from the substrate/film interface is reflected by the poor existence of conducting pathways that connect the top and bottom planes of the film. The three-dimensional morphology of this polymer blend that is revealed thanks to the employed techniques deviates substantially from the ideal morphology proposed for the efficient performance of the targeted memory devices.Advanced Materials by DesignInitiative d'excellence de l'Université de Bordeau

Jahresübersicht Simulation gießtechnischer Prozesse (1. Folge), Teil 1: Anwendungen

Printed organic photodetectors can transform plastic, paper or glass into smart surfaces. This innovative technology is now growing exponentially due to the strong demand in human-machine interfaces. To date, only niche markets are targeted since organic sensors still present reduced performances in comparison with their inorganic counterparts. Here we demonstrate that it is possible to engineer a state-of-the-art organic photodetector approaching the performances of Si-based photodiodes in terms of dark current, responsivity and detectivity. Only three solution-processed layers and two low-temperature annealing steps are needed to achieve the performance that is significantly better than most of the organic photodetectors reported so far. We also perform a long-term ageing study. Lifetimes of over 14,000 hours under continuous operation are more than promising and demonstrate that organic photodetectors can reach a competitive level of stability for successful commercialization of this new and promising technology

Thermosensitive Hybrid Elastin-like Polypeptide-Based ABC Triblock Hydrogel

We report the synthesis of a well-defined hybrid ABC triblock terpolymer containing a synthetic poly(trimethylene carbonate) (PTMC) block A and a thermosensitive BC diblock of recombinant elastin-like polypeptides (ELPs). The triblock in diluted solution (0.1–0.3% w/v), at low temperatures in ultrapure water, forms micellar structures of 10–60 nm sizes in diameter as characterized by dynamic light scattering (DLS) and liquid atomic force microscopy (AFM). While heated above its transition temperature (Tt), larger particles of 200–300 nm sizes are obtained, consistent with the formation of coacervates. When concentrated, the viscosity of the triblock copolymer solution progressively increases, giving a free-standing gel at 4% w/v formed by a network of micron-sized particles. The formed hydrogels are thermally reversible, and their sol–gel transitions are fast and sharp. The gel formation mechanism appears to interestingly biomimic tropoelastin, the native monomeric form of natural elastin, as demonstrated by optical and cryogenic-scanning electron microscopy (cryo-SEM) imaging

Optimization of Magnetic Inks Made of L10-Ordered FePt Nanoparticles and Polystyrene-block-Poly(ethylene oxide) Copolymers.

The preparation of magnetic inks stable over time made of L10-ordered FePt nanoparticles, thiol-ended poly(ethylene glycol) methyl ether (mPEO-SH) compatibilizing macromolecules and asymmetric polystyrene-block-poly(ethylene oxide) copolymers (BCP) as a subsequent self-organizing medium was optimized. It was demonstrated that the use of sacrificial MgO shells as physical barriers during the annealing stage for getting the L10-ordered state makes easier and more efficient the anchoring of compatibilizing PEO macromolecules onto the nanoparticles surface. L10-FePt grafted nanoparticles have shown a good colloidal stability and affinity with the PEO domains of the BCP leading to L10-FePt/BCP composite thin layers with individual magnetic dots dispersed in the BCP matrix.

Photoactive Donor−Acceptor Composite Nanoparticles Dispersed in Water

A major issue that inhibits large-scale fabrication of organic solar modules is the use of chlorinated solvents considered as toxic and hazardous. In this work, composite particles of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2’,1’,3’-benzothiadiazole] (PCDTBT) and [6,6]-Phenyl C71 butyric acid methyl ester (PC71BM) were obtained in water from a versatile and a ready-to-market methodology based on post-polymerization miniemulsification. Depending on experimental conditions, size-controlled particles comprising both the electron-donor and the electron-acceptor were obtained and characterized using transmission electron microscopy (TEM), atomic force microscopic (AFM), small-angle neutron scattering (SANS), UV-visible absorption and fluorescence spectroscopies. Intimate mixing of the two components was definitely asserted through PCDTBT fluorescence quenching in the composite nanoparticles. The water-based inks were used for the preparation of photovoltaic active layers which were subsequently integrated in organic solar cells

Loading linear arrays of Cu(II) inside aromatic amide helices

The very stable helices of 8‐amino‐2‐quinolinecarboxylic acid oligoamides are shown to uptake Cu(II) ions in their cavity through deprotonation of their amide functions with minimal alteration of their shape, unlike most metallo‐organic structures which generally differ from their organic precursors. The outcome is the formation of intramolecular linear arrays of a defined number of Cu(II) centers (up to sixteen in this study) at a 3 Å distance, forming a molecular mimic of a metal wire completely surrounded by an organic sheath. The helices pack in the solid state so that the arrays of Cu(II) extend intermolecularly. Conductive‐AFM and cyclic voltammetry suggest that electrons are transported throughout the metal‐loaded helices in contrast with hole transport observed for analogous foldamers devoid of metal ions