Eric Cloutet

Synthesis of Biobased Polyurethane from Oleic and Ricinoleic Acids as the Renewable Resources via the AB-Type Self-Condensation Approach

Polyurethane (PU) from methyl oleate (derived from sunflower oil) and ricinoleic acid (derived from castor oil) was synthesized using the AB-type self-polycondensation approach for the first time. In the present work, three novel AB-type monomers, namely, a mixture of 10-hydroxy-9-methoxyoctadecanoyl azide/9-hydroxy-10-methoxyoctadecanoyl azide (HMODAz), 12-hydroxy-9-cis-octadecenoyl azide (HODEAz) and methyl-N-11-hydroxy-9-cis-heptadecen carbamate (MHHDC) were synthesized from methyl oleate and ricinoleic acid using simple reaction steps. Out of these, HMODAz and HODEAz monomers were polymerized by the acyl-azido and hydroxyl AB-type self-condensation approach, while MHHDC monomer was polymerized through AB-type self-condensation via transurethane reaction. The acyl-azido and hydroxyl self-condensations were carried out at various temperatures (50, 60, 80. and 110 degrees C) in bulk with and without catalyst. A FTIR study of the polymerization, using HMODAz at 80 degrees C without catalyst, indicates in situ formation of an intermediate isocyanate group in the first 15-30 min, and further onward, the molar mass increases as observed by SEC analysis. In the case of the MHHDC monomer, a transurethane reaction was used to obtain a similar PU (which was obtained by AB-type acyl-azido and hydroxyl self-condensation of HODEAz) in the presence of titanium tetrabutoxide as a catalyst at 130 degrees C. HMODAz, HODEAz, MHHDC, and corresponding polyurethanes were characterized by FTIR, (1)H NMR, (13)C NMR, and MALDI-TOF mass spectroscopy. Differential scanning calorimetric analysis of polyurethanes derived from HMODAz, HODEAz, and MHHDC showed two different glass transition temperatures for soft segments (at lower temperature) and hard segments (at higher temperature), indicating phase-separated morphology.

Solubility in CO2 and carbonation studies of epoxidized fatty acid diesters: towards novel precursors for polyurethane synthesis

Novel linear polyurethanes were synthesized by bulk polyaddition of diamines with two vegetable-based biscarbonates produced from oleic acid methyl ester. Internal carbonated fatty acid diester (ICFAD) and terminal carbonated fatty acid diester (TCFAD) were obtained by the reaction of their epoxide precursors with CO2. Terminal epoxy fatty acid diester (TEFAD) was found to be more soluble and more reactive in CO2 than internal epoxy fatty acid diester (IEFAD). Polyurethanes obtained by polyaddition of TCFAD and ICFAD with diamines exhibit molecular weights up to 13 500 g mol−1 and glass transitions around −15 °C. Amide linkages were not observed when secondary diamine was used as the comonomer.

Thermal Stabilisation of Polymer–Fullerene Bulk Heterojunction Morphology for Efficient Photovoltaic Solar Cells

A novel stable bisazide molecule that can freeze the bulk heterojunction morphology at its optimized layout by specifically bonding to fullerenes is reported. The concept is demonstrated with various polymers: fullerene derivatives systems enable highly thermally stable polymer solar cells.

Cross Olefin Metathesis for the Selective Functionalization, Ferrocenylation, and Solubilization in Water of Olefin-Terminated Dendrimers, Polymers, and Gold Nanoparticles and for a Divergent Dendrimer Construction

Olefin cross metathesis was used to efficiently functionalize polyolefin dendrimers, polymers, and gold nanoparticles using the second-generation Grubbs catalyst. In these structures, the tethers were lengthened to prevent the facile cross metathesis that otherwise predominates in polyolefin dendrimers having short tethers. This synthetic strategy allows the one-step access to polyacid, polyester, and polyferrocenyl structures from polyolefins. Cross metathesis is also used to efficiently achieve an iterative divergent dendritic construction. All the cross metathesis reactions were monitored by 1H NMR showing the chemo-, regio-, and stereoselectivity. MALDI-TOF mass spectrometry was a very useful technique to confirm the efficiency of this synthetic strategy.

Block Copolymer as a Nanostructuring Agent for High‐Efficiency and Annealing‐Free Bulk Heterojunction Organic Solar Cells

The addition of a block copolymer to the polymer/fullerene blend is a novel approach to the fabrication of organic solar cells. The block copolymer (P3HT-b-P4VP) is used as nanostructuring agent in the active layer. A significant enhancement of the cell efficiency is observed, in correlation with morphology control, both before (as-cast) and after the annealing process.

Optimization of the Bulk Heterojunction Composition for Enhanced Photovoltaic Properties: Correlation between the Molecular Weight of the Semiconducting Polymer and Device Performance

Herein we propose an approach toward the optimization of the photovoltaic performance of bulk heterojunctions by tuning the composition of the active layer with respect to the molecular weight of the semiconducting polymer. We used a poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend as a typical system and varied the molecular weight of the P3HT semiconducting polymer in order to determine its influence on the bulk heterojunction morphology as well as on the optoelectronic characteristics of the device. We have systematically mapped out the phase diagram for different molecular weight P3HTs blended with PCBM and observed the presence of a eutectic composition, which shifts to higher content of P3HT for lower molecular weight P3HTs. This shift inherent to the P3HT molecular weight is also apparent in the photovoltaic performance as the eutectic composition corresponds to the best of the photovoltaic properties. The P3HT molecular weight dependence of the eutectic composition is due to the molecular weight dependence of the P3HT crystallization behavior, which leads to dramatic morphological changes of the bulk heterojunction.

Synthesis and blue luminescence of a soluble newly designed carbazole main-chain polymer

A new electroactive polymer with alternating conjugated–nonconjugated repeating units in the main chain was synthesized by step growth polymerization of α,ω-bis(N-carbazolyl)octane in chloroform solution with excess of iron trichloride, and in the presence of N-ethylcarbazole as a terminating agent. The resulting α,ω-N-ethylcarbazole terminated poly(3,3′-bicarbazyl-N,N′-octylene)s are readily soluble in common organic solvents and have good film-forming capabilities, partly because of the special design of the polymer backbone constituted by stiff bicarbazyl chromophores linked by flexible eight-carbon segments. Soluble materials with molecular weights up to 105 g/mol and polydispersity indices around 3.3 were obtained. Purified samples exhibiting quite low polydispersity indices (in the range 1.5–1.7) can be prepared by a selective fractionation of the crude polymer from benzene/methanol mixtures. Structural analysis of these new ‘stairs-like’ polymers disclosed their well-defined character with an aromatic linkage exclusively at position 3 on the carbazole moieties. Electrochemical studies of polymer films exhibited two reversible redox processes between 0 and 1.5 V vs saturated calomel electrode. The photoluminescence (PL) of the polymer in solution and as cast films revealed an intense blue emission and the same intensity level than that of the N,N′-diethyl-3,3′-bicarbazyl molecule, taken as a model of the aromatic segment of the repeating unit. Such a processable and purifiable polymer with bicarbazyl-isolated fluorophores is quite promising for the fabrication of efficient blue light-emitting devices.

The First Organometallic Dendrimers: Design and Redox Functions

This review summarizes our original organometallic route to stars, dendrimers, metallostars and metallodendrimers and the redox functions of these macromolecules in catalysis and anionic recognition. The synthesis of metal-sandwich stars and dendritic cores was achieved using the CpM+ induced polyallylation and polybenzylation of polymethylbenzenes (M = Fe or Ru) and pentamethylcyclopentadienyl ligands (M = Co or Rh). Subsequent functionalization of the polyallyl dendritic cores yielded polyols which are precursors of polyiodo, polymesylates, polynitriles, polyamines and polybenzaldehaldehyde cores. The synthesis of dendrimers up to 144-nitrile and 243-allyl was subsequently achieved starting from mesitylene. Functionalization of the polybenzyl dendritic cores was achieved by regiospecific Friedel-Crafts reactions (acetylation, chlorocarbonylation) in the para position. Various metallodendrimers were synthesized with amidoferrocene, amidocobaltocenium and FeCp*(η 6-N-alkylaniline)+ termini in which the redox centers show a reversible behavior and are all independent as observed by cyclic voltammetry. The 9-, 18- and 24-amidometallocene dendrimers were used for the recognition of the oxo anions H2PO 4 − and HSO 4 − by cyclic voltammetry, whereas a 24-iron-alkylaniline dendrimer was efficient to recognize Cl− and Br− anions by 1H NMR with sharp dendritic effects. Differences between the responses to the different anions were large and the largest effects were found for the 18-Fc dendrimer (dendritic effect). A water-soluble star-shaped hexa-iron redox catalyst was as efficient as the mononuclear species for the cathodic reduction of NO 3 − and NO 2 − in water. In conclusion, metallostars are suitable for catalysis, and metallodendrimers present optimal topologies for molecular recognition. These specific functions related to the topologies cannot be interchanged between the metallostars and the metallodendrimers with optimized efficiency in the present examples.

On the chemical fixation of supercritical carbon dioxide with epoxides catalyzed by ionic salts: an in situ FTIR and Raman study

A series of ionic salts have been investigated to catalyze the coupling reaction between epoxide and carbon dioxide at T = 80 °C and P = 8 MPa. Among them, we focused particularly on tetrabutylammonium, imidazolium and guanidinium salts. The kinetics of the synthesis was monitored in situ using both FTIR and Raman spectroscopy. For a given reaction time, the best yields were obtained with 1,5,7-triaza-bicyclo[4.4.0]dec-5-enium bromide (TBD·HBr) and 1-methyl-3-methylimidazolium iodide (MMImI) and both have not been investigated in detail in the literature before. Thanks to this catalyst screening, we have verified how some functional groups of the catalyst can activate the epoxide and the CO2 molecule enabling us to go further in the mechanism comprehension of this reaction. Due to its easier and less expensive synthesis than other ionic liquids, we focused more particularly on TBD·HBr that also offers a good conversion rate even at low pressure (80 °C and 1 MPa).

Synthesis and self-assembly of polythiophene-based rod–coil and coil–rod–coil block copolymers

Block copolymers constituted of flexible poly(n-butyl acrylate) or poly(tert-butyl acrylate) and rigid poly(3-hexylthiophene) segments have been synthesized by atom transfer radical polymerization and by oxidative polymerization accordingly. Two synthetic routes were followed to obtain rod–coil or coil–rod–coil block copolymers. The self-assembly of the copolymers in solution in a selective solvent of the flexible block was studied by means of static and dynamic light scattering.