Radiation-induced reduction-polymerization route for the synthesis of PEDOT conducting polymers

Synthesis of conducting poly(3,4-ethylenedioxythiophene), PEDOT, is achieved through an original reduction-polymerization route: γ-radiolysis of aqueous solutions containing EDOT monomers under N2 atmosphere. According to UV-vis absorption spectrophotometry and ATR-FTIR spectroscopy, reduction of EDOT is initiated by hydrated electrons produced by water radiolysis and leads to PEDOT polymers through coupling reactions. The morphology of PEDOT is characterized by Cryo- TEM microscopy in aqueous solution and by SEM after deposition. In an original way, high resolution AFM microscopy, coupled with infrared nanospectroscopy, is used to probe the local chemical composition of PEDOT nanostructures. The results demonstrate that spherical self-assembled PEDOT nanostructures are formed. TGA analysis and four point probe measurements demonstrate that thermal stability and electrical conductivity of PEDOT polymers obtained by the present original reduction-polymerization method are close to those of PEDOT we previously prepared by radiolysis according to an oxidation-polymerization route

Optimal strategy based on radiation chemistry for facile and direct synthesis of poly(3-thiophene acetic acid) polymers in water and dichloromethane

In this work, synthesis of nanostructured conducting poly(3-thiophene acetic acid) (PTAA) polymers was developed by means of γ-induced oxidative polymerization of TAA monomers dissolved either in water or in dichloromethane. This synthesis was shown to be facile and directly feasible without any prior esterification of TAA and in the absence of oxidizing agents. Radiolytic yields of TAA oxidation as well as irradiation doses required for quantitative PTAA preparation were determined for each solvent. UV-Vis and ATR-FTIR spectroscopies demonstrated the successful formation of two PTAA polymers, so-called "PTAAH2O"and "PTAACH2Cl2". Size exclusion chromatography (SEC) highlighted convergent molecular weight values corresponding to approximately 13 monomer units. A similar behavior for both radio-synthesized PTAAs was monitored by thermogravimetric analysis (TGA). The morphological structures of PTAAH2O and PTAACH2Cl2 were analyzed in solution by Cryo-TEM and after deposition by SEM and AFM. Microscopic observations revealed the presence of two distinguishable nanostructures: nano-spherules of several hundreds of nanometers made of PTAAH2O and nano-granules of several tens of nanometers made of PTAACH2Cl2. Cyclic voltammetry analysis and the Tauc plot method were employed to calculate the electrical and optical band gaps. Both polymers possess similar electrical band gaps. However, PTAACH2Cl2 affords a lower optical band gap than PTAAH2O. Four-point probe measurements showed that the radio-synthesized PTAA polymers are characterized by interesting electrical properties: a higher electrical conductivity was nevertheless recorded for PTAACH2Cl2. This study highlights the powerful ability of the radiation chemistry-based methodology to lead, as a simple, versatile and reliable method, to nanostructured PTAA conducting polymers either in aqueous or organic solutions

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications

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Pseudo-capacitors using stable n-doped conducting polymers combined to aligned carbon nanotubes

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Signal enhancement of electrochemical biosensors via direct electrochemical oxidation of silver nanoparticle labels coated with zwitterionic polymers

International audienceA new electrochemical label has been developed, which is made up of silver nanoparticles (AgNPs) coated with a mixture of zwitterionic and biotinylated zwitterionic polymers. These polymers improve colloidal stability in physiological medium and ensure biorecognition while direct electrochemical oxidation of silver nanoparticles strongly enhances the detection signal. The resulting hybrid nanomaterials are used as labels in the electrochemical sensing of avidin using sandwich assays elaborated using the biotin-avidin biorecognition system

Synthesis and electro-optical properties of polyfluorene modified with randomly distributed electron-donor and rotaxane electron-acceptor structural units in the main chain

International audiencePolyfluorene PF•γCD rotaxane copolymer, composed of randomly distributed 9,9-dioctylfluorene, methyltriphenylamine (electron-donating) and 9-dicyanomethylenefluorene complexed with γ-cyclodextrin (γCD) (electron-accepting) structural units, has been synthesized by Suzuki cross-coupling reaction. The chemical structures were proved by FTIR and 1H NMR spectroscopy. The surface morphology, thermal, optical, electrochemical behavior, and adhesion characteristics of the obtained rotaxane copolymer have been investigated and compared with those of the nonrotaxane counterpart (PF). Relatively high fluorescence efficiency, almost identical normalized absorbance maximum in solution and solid-state of PF•γCD rotaxane copolymer, and a more uniform and smoother surface with lower adhesion forces provides the role of γCD encapsulation on the lower aggregation propensity. PF•γCD and PF copolymers exhibit n- and p-doping processes and blue-light emission in the film state. The optical and electrochemical band gaps (ΔEg), as well as the highest occupied molecular orbital/lowest unoccupied molecular orbital positions in an energetic diagram indicate that both copolymers are promising blue-emitting electroluminescent materials. Copyrigh

Combination of thiophene-based polymer and vertically aliged carbon nanotubes for n-doping based negative electrodes of pseudocapacitors with high energy and power densities

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Pseudo-capacitors using n-doped conducting polymers combined to aligned carbon nanotubes

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