Synthèse de Poly(3,4-ethylènedioxythiophène) en milieux dispersants organiques

L objectif de ce travail de thèse était de développer des encres organiques de polymères semi-conducteurs. Il s est ainsi agi de synthétiser des latex de poly (3,4-éthylènedioxythiophène) (PEDOT) dispersibles en milieux organiques (cyclohexane ou toluène) par polymérisation oxydative de l EDOT en présence de stabilisant stériques et/ou électrostatiques. Le stabilisant est un polymère fonctionnalisé par une unité ou plusieurs unités fonctionnelles qui peuvent réagir avec la chaîne de PEDOT en croissance assurant ainsi des liaisons covalentes ou électrostatiques entre celui-ci et le stabilisant. La taille des particules de PEDOT est contrôlée par la masse molaire, la concentration et par la fonctionnalité du stabilisant. Le PEDOT obtenu est caractérisé par diffusion de la lumière (DLS), par microscopie électronique à balayage (MEB) microscopie électronique à transmission (TEM) et par des mesures de conductivité.Spherical poly(3,4-ethylenedioxythiophene) nano-particles with narrow size distribution were prepared in organic dispersant media in the presence of iron(III) chloride FeCl3 or iron(III) dodecylbenzenesulfonate {Fe(DBS)3} as oxidant and a functionalized polyisoprene ( -R-PI) as a stabilizer. Two kinds of functionalized polyisoprene were used as stabilizers. Pyrrole, fluorene, Thiophene and methylthiophene end caped polyisoprenes were used as reactive stabilizers. Lithium sulfonate end caped polyisoprene was used as steric stabilizer. The effect of the nature of the solvent, the molar mass, the concentration, and the nature of the functional end unit of the stabilizer on the size and morphology of PEDOT particles were investigated. Polyisoprenes containing sulfonate groups were also used as steric/electrostatic stabilizers. By this way, the sulfonate groups act as counter ions for oxidized PEDOT leading to electrostatic attraction between it and the stabilizer, ensuring stabilization of the latex. Four kinds of polyisoprene-based steric electrostatic stabilizers having one or many sulfonate groups were prepared: sulfonate end-capped polyisoprene (PI-SO3Li), partially sulfonated polyisoprene (PIS), polyisoprene grafted to polystyrene sulfonate (PI-g-PSS) and polyisoprene grafted to polyisoprene sulfonate (PI-g-PIS). The effects of the molar mass of the stabilizer and the sulfonate group content on the PEDOT particle morphology were studied.PEDOT samples were characterized with transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic light scattering (DLS) analysis and conductivity measurements.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Synthèse de copolymères de type polymère semi-conducteur-bloc-polymère hydrosoluble (application à la dispersion de nanotubes de carbone)

Cette thèse porte pour l'essentiel sur la synthèse de copolymères à blocs bien définis composés au moins d'un bloc polymère semi-conducteur et d'un segment hydrosoluble pour être utilisés comme agents dispersants de nanotubes de carbone (NTCs) dans des milieux aqueux. Des copolymères de différentes masses molaires ont été synthétisés en suivant des procédés de polymérisation sans métaux et l influence de la fraction volumique de la partie hydrosoluble a été étudiée au regard de leur solubilité en milieux aqueux. La capacité de ces copolymères à s'organiser ou s'auto-assembler tant en solution qu'en film a été examinée. Enfin, des dispersions de NTCs avec ces copolymères ainsi que leurs films obtenus par différents types de dépôts ont été réalisés et caractérisés pour déterminer notamment leurs caractéristiques électro-optiques.Our work focused on the synthesis of well-defined copolymers constituted with at least a conductive polymer segment along with hydrophilic moieties in order to disperse CNTs in aqueous media. Using metal free polymerizations, copolymers with different molecular weights were synthesized in order to study the influence of the hydrophilic part on these materials. Besides the self-assembly behavior of these copolymers, both in bulk and in solution, were addressed. This type of copolymers were successfully used to disperse both single and multi wall carbon nanotubes. Electrical and optical characteristics of the dispersions together with their films will also be discussed.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Biohybrid plants with electronic roots via in vivo polymerization of conjugated oligomers

Plant processes, ranging from photosynthesis through production of biomaterials to environmental sensing and adaptation, can be used in technology via integration of functional materials and devices. Previously, plants with integrated organic electronic devices and circuits distributed in their vascular tissue and organs have been demonstrated. To circumvent biological barriers, and thereby access the internal tissue, plant cuttings were used, which resulted in biohybrids with limited lifetime and use. Here, we report intact plants with electronic functionality that continue to grow and develop enabling plant-biohybrid systems that fully maintain their biological processes. The biocatalytic machinery of the plant cell wall was leveraged to seamlessly integrate conductors with mixed ionic-electronic conductivity along the root system of the plants. Cell wall peroxidases catalyzed ETE-S polymerization while the plant tissue served as the template, organizing the polymer in a favorable manner. The conductivity of the resulting p(ETE-S) roots reached the order of 10 S cm(-1) and remained stable over the course of 4 weeks while the roots continued to grow. The p(ETE-S) roots were used to build supercapacitors that outperform previous plant-biohybrid charge storage demonstrations. Plants were not affected by the electronic functionalization but adapted to this new hybrid state by developing a more complex root system. Biohybrid plants with electronic roots pave the way for autonomous systems with potential applications in energy, sensing and robotics

Chitosan-Modified Polyethyleneimine Nanoparticles for Enhancing the Carboxylation Reaction and Plants' CO2 Uptake

Increasing plants' photosynthetic efficienc y is a major challenge that must be addressed in order to cover the food demands of the growing population in the changing climate. Photosynthes i s is greatly limited at the initial carboxylation reaction, where CO2 is converted to the organic acid 3-PGA, catalyzed by the RuBisCO enzyme. RuBisCO has poor affinity for CO2, but also the CO2 concentration at the RuBisCO site is limited by the diffusion of atmospheric CO2 through the various leaf compartments to the reaction site. Beyond genetic engineer-ing, nanotechnology can offer a materials-based approach for enhancing photosynthesis, and yet, it has mostly been explored for the light-dependent reactions. In this work, we developed polyethyleneimine-based nanoparticl e s for enhancing the carbox-ylation reaction. We demonstrate that the nanoparticles can capture CO2 in the form of bicarbonate and increase the CO2 that reacts with the RuBisCO enzyme, enhancing the 3-PGA production in in vitro assays by 20%. The nanoparticles can be introduced to the plant via leaf infiltration and, because of the functionalization with chitosan oligomers, they do not induce any toxic effect to the plant. In the leaves, the nanoparticles localize in the apoplastic space but also spontaneously reach the chloroplasts where photosynthetic activity takes place. Their CO2 loading-dependent fluorescence verifies that, in vivo, they maintain their abi l i t y to capture CO2 and can be therefore reloaded with atmospheric CO2 while in planta. Our results contribute to the development of a nanomaterials-based CO2-concentrating mechanism in plants t h a t can potentially increase photosynthetic efficiency and overall plants' CO2 storage

Enhanced Electrocaloric Response of Vinylidene Fluoride–Based Polymers via One‐Step Molecular Engineering

Electrocaloric refrigeration is one of the most promising environmentally-friendly technologies to replace current cooling platforms—if a notable electrocaloric effect (ECE) is realized around room temperature where the highest need is. Here, a straight-forward, one-pot chemical modification of P(VDF-ter-TrFE-ter-CTFE) is reported through the controlled introduction of small fractions of double bonds within the backbone that, very uniquely, decreases the lamellar crystalline thickness while, simultaneously, enlarging the crystalline coherence along the a-b plane. This increases the polarizability and polarization without affecting the degree of crystallinity or amending the crystal unit cell—undesirable effects observed with other approaches. Specifically, the permittivity increases by >35%, from 52 to 71 at 1 kHz, and ECE improves by >60% at moderate electric fields. At 40 °C, an adiabatic temperature change >2 K is realized at 60 MV m−1 (>5.5 K at 192 MV m−1), compared to ≈1.3 K for pristine P(VDF-ter-TrFE-ter-CTFE), highlighting the promise of a simple, versatile approach that allows direct film deposition without requiring any post-treatment such as mechanical stretching or high-temperature annealing for achieving the desired performance

Synthèse de (co)polymères à base de Poly(3-hexylthiophène) pour le photovoltaïque organique

L optimisation de la morphologie de la couche active est primordiale pour l augmentation des rendements des cellules solaires photovoltaïques organiques. Nous avons montré l influence du ratio de matériaux donneur (P3HT) et accepteur (PCBM) d électrons ainsi que de la masse molaire du P3HT sur la morphologie de la couche active. Afin de contrôler la séparation de phases entre les matériaux donneur et accepteur d électrons, il est possible d utiliser des copolymères à blocs afin d aider la compatibilisation entre le P3HT et le PCBM. Nous avons choisi de synthétiser des copolymères à blocs P3HT-b-polystyrène et des P3HT-b-polyisoprène présentant une certaine compatibilité avec les matériaux de la partie active. L ajout optimisé de P3HT-b-polyisoprène permet une augmentation de 30% des rendements et de 90% de durée de vie des cellules solaires.Active layer morphology optimization is fundamental to achieve high efficiency in organic photovoltaic solar cells. We showed the influence of the donor (P3HT) and acceptor (PCBM) material ratio and the impact of the P3HT molecular weight on the active layer morphology. We demonstrated the possibility of using well-designed block copolymers to help P3HT and PCBM compatibilization and to control their phase separation. We chose to synthesize P3HT-b-polystyrene and P3HT-b-polyisoprene for which each block is compatible with the active materials. Optimal addition of P3HT-b-polyisoprene enables to get a 30%-improved efficiency and a 90%-enhanced lifetime of the solar cells.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Design de nouveaux synthons dérivés de l'acide oléique (application à la synthèse de polyuréthanes)

De nouveaux synthons bio-sourcés de structure et de fonctionnalité contrôlées ont été préparés à partir de l oléate de méthyle issu de l huile de tournesol. Les synthons de type C18-R-C18 et de nature diol et biscarbonate ont ensuite été utilisés pour la synthèse de polyuréthanes thermoplastiques. Selon la nature de R (aliphatique ou aromatique), les propriétés thermomécaniques et rhéologiques de ces polyuréthanes on été ajustées. Dans le cas où R est hydrophile, les synthons de types diols présentent des propriétés amphiphiles permettant la préparation de polyuréthanes en dispersion aqueuse. Pour s affranchir del utilisation d isocyanates, des polyuréthanes ont été préparés par réaction de diamines avec les synthons biscarbonates. Ces derniers ont été synthétisés par réaction de leurs homologues époxydés avec le CO2.AbstractBORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Synthesis of core-shell polyurethane-polydimethylsiloxane particles by polyaddition in organic dispersant media: Mechanism of particle formation

Core-shell polyurethane (PUR)-polydimethylsiloxane (PDMS) particles were prepared by polyaddition between ethylene glycol and tolylene-2,4-diisocyanate in cyclohexane, used as the organic dispersant phase, in the presence of reactive hydroxy-terminated polydimethylsiloxane steric stabilizers. The reaction extent and the PUR particle size, monitored by FTIR, H-1 NMR, SEC, SEM and TEM techniques against time, were found a function of the PDMS concentration, functionality and molar mass. A mechanism of the polyurethane particle growth is proposed on the grounds of the kinetic investigation

Synthesis and photovoltaic applications of novel copolymers based on poly(3-hexylthiophene)

Dans cette étude, des copolymères à blocs rigide-flexible comprenant des segments donneur [poly(3-hexylthiophène) régiorégulier, (rr-P3HT)] et accepteurs d électrons (C60) ont été synthétisés. L auto-assemblage en masse de ces copolymères à blocs avait pour objectif d atteindre des morphologies dont la taille des domaines coïncide avec la distance idéale de transport de l exciton (~10 nm) en vue d utiliser ces systèmes comme matériaux de couche active dans les cellules photovoltaïques organiques de type P3HT-PCBM.La maîtrise et l'optimisation des conditions de synthèse de rr-P3HT de fonctionnalité terminale bien définie nous ont permis d'accéder à différentes architectures de copolymères linéaires di- et triblocs, constitués de P3HT comme bloc rigide et de polystyrène ou poly(4-vinylpyridine) comme bloc flexible . La fonctionnalisation du bloc flexible avec des dérivés du fullerène (C60 ou PCBM) a ensuite été réalisée et ces copolymères utilisés comme additifs pour stabiliser la morphologie de la couche active des cellules solaires organiques de type P3HT/PCBM. Les caractéristiques photovoltaïques des matériaux ainsi préparés ont été déterminées et corrélées aux analyses morphologiques de la couche active.The performance of organic photovoltaic cells mainly depends on the active layer nano-morphology. Rod-coil block copolymers (BCPs) are well known in their ability to self-assemble into well-ordered nanoscopic morphologies. BCPs containing electron-donor and acceptor segments are of particular interest for use in photovoltaic cells because electronic light-excited states exist over distances similar to the typical size of block copolymer domains (~10 nm). Therefore, we designed novel donor-acceptor BCPs to exploit this coincidence in dimensions. This thesis is focused on BCPs based on regioregular poly(3-hexylthiophene) (rr-P3HT) due to its high hole mobility and good processibility from various solvents. Simplified and versatile syntheses of donor-acceptor rod-coil di- and tri- BCPs consisting of the donor block P3HT (rod) and polystyrene or poly(4-vinylpyridine) (coil) blocks to carry the acceptor C60 in different ways were developed. These materials were used as surfactants to stabilize the nano-morphology of reference P3HT: [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) based devices. Photovoltaic characterizations were then tied to copolymer structural data with the help of AFM and a range of complementary characterization techniques.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF