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Bruno Ameduri - One of the best experts on this subject based on the ideXlab platform.

  • recent progress on core shell structured batio3 polymer fluorinated polymers nanocomposites for high energy storage synthesis dielectric properties and applications
    Progress in Materials Science, 2020
    Co-Authors: Fatima Ezzahra Bouharras, Mustapha Raihane, Bruno Ameduri
    Abstract:

    Abstract This review aims at updating various studies to design BaTiO3@polymer/Fluoropolymer nanocomposites, to study their properties and performances and to supply their applications. Dielectric nanocomposite materials with high energy density exhibit promising performances for energy storage applications. Major efforts have been performed to combine the efficient properties and high dielectric constant of ceramics with the flexibility and easy processing of polymers. Actually, the dielectric properties of the nanocomposite are influenced by the dielectric features of both ceramic and polymer. Thus, the choice of the two components become crucial in turning the desired properties. Another important factor is the modification strategy to get such nanocomposites, where the major routes are the “grafting from”, “grafting onto” and melt process while most Fluoropolymers studied are polyvinylidene fluoride (PVDF), VDF containing-copolymers and terpolymers and poly(acrylates) bearing fluoroalkyl side groups. Additionally, fluorinated silanes have also been involved in sol–gel chemistry to decorate BaTiO3 surface, as well as tetrafluorophthalic acid or fluorinated dopamine did. This review also summaries the current state of high energy density nanocomposites based on BaTiO3 as a ceramic nanofiller and fluoropolymer as matrix.

  • The Promising Future of Fluoropolymers
    Macromolecular Chemistry and Physics, 2020
    Co-Authors: Bruno Ameduri
    Abstract:

    This article aims at showing the usefulness of Fluoropolymers (PFs), supplying a browse on their synthesis, applications and recycling. FPs are currently prepared by conventional radical polymerization of fluoromonomers. These specialty polymers, produced in low tonnage compared to that of commodity ones, display outstanding properties such as chemical, oxidative and thermal resistances, low refractive index, dissipation factor, permittivity, and water absorptivity, and excellent weatherability and durability. More recent routes for their preparations are suggested, controlled or not, leading to random, alternated, block, graft, dendrimers or multiarm copolymers, as well as their applications ranging from coatings to high performance (thermoplastic) elastomers, energy related-materials (e.g. fuel cell membranes, components for Lithium ion batteries, electroactive devices, and photovoltaics) to original and surfactants, optical devices, organic electronics, composites and shape memory polymers.

  • molecular aggregation structure and surface properties of biomimetic catechol bearing poly 2 perfluorooctyl ethyl acrylate and its application to superamphiphobic coatings
    ACS Omega, 2020
    Co-Authors: Bruno Ameduri, Atsushi Takahara
    Abstract:

    The molecular aggregation structure and surface properties of a catechol-bearing fluoropolymer, P(FAC8-co-DOPAm), which was synthesized by conventional radical copolymerization of 2-(perfluorooctyl...

  • 19f dosy diffusion nmr spectroscopy of Fluoropolymers
    Magnetic Resonance in Chemistry, 2017
    Co-Authors: Yingbo Wan, Bruno Ameduri, Dongxue Chen, Chun Gao, Hongnan Yin, Daniel Fetherston, Eriks Kupce, Gerald Lopez, Eric B Twum
    Abstract:

    A new pulse sequence for obtaining 19 F detected DOSY (diffusion ordered spectroscopy) spectra of fluorinated molecules is presented and used to study Fluoropolymers based on vinylidene fluoride and chlorotrifluoroethylene. The performance of 19 F DOSY NMR experiments (and in general any type of NMR experiment) on Fluoropolymers creates some unique complications that very often prevent detection of important signals. Factors that create these complications include: (1) the presence of many scalar couplings among 1 H, 19 F and 13 C; (2) the large magnitudes of many 19 F homonuclear couplings (especially 2 JFF ); (3) the large 19 F chemical shift range; and (4) the low solubility of these materials (which requires that experiments be performed at high temperatures). A systematic study of the various methods for collecting DOSY NMR data, and the adaptation of these methods to obtain 19 F detected DOSY data, has been performed using a mixture of low molecular weight, fluorinated model compounds. The best pulse sequences and optimal experimental conditions have been determined for obtaining 19 F DOSY spectra. The optimum pulse sequences for acquiring 19 F DOSY NMR data have been determined for various circumstances taking into account the spectral dispersion, number and magnitude of couplings present, and experimental temperature. Pulse sequences and experimental parameters for optimizing these experiments for the study of Fluoropolymers have been studied. Copyright © 2016 John Wiley & Sons, Ltd.

  • Crosslinking of vinylidene fluoride-containing Fluoropolymers
    Advances in Polymer Science, 2005
    Co-Authors: Aurélie Taguet, Bruno Ameduri, Bernard Boutevin
    Abstract:

    Fluoropolymers are well-known for their good properties in terms of chemical, thermal and electrical stabilities, inertness to acids, bases, solvents and oils, and high resistance to ageing and oxidation. Polyvinylidene fluoride (PVDF) is useful as a homopolymer endowed with interesting characteristics. It contains a high crystallinity rate, but is base sensitive. In addition, VDF can be co- or terpolymerized with several fluorinated monomers, rendering them suitable as elastomers and various examples of synthesis of VDF-copolymers are also presented. This review also focusses on binary and tertiary systems containing VDF. Several curing systems for these VDF-containing copolymers have been investigated, especially diamines and their derivatives, aromatic polyhydroxy compounds, peroxides with coagents, such as triallylisocyanurate, radiations, and thiol-ene systems. The best vulcanizate properties are obtained by a two-step process. First, the material is press cured at different times and temperatures, then, it is post cured in air or under nitrogen at higher temperature and time, and under atmospheric pressure. Poly(VDF-co-HFP) copolymers can react with primary, secondary or tertiary monoamines, but they are mainly crosslinked by diamines such as hexamethylene diamine (HMDA), their carbamates (HMDA-C), and derivatives. A mechanism of crosslinking is identified by Infrared and 19F NMR spectroscopies, and was evidenced to proceed in three main steps. First, a VDF unit undergoes a dehydrofluorination in the presence of the diamine, then the Michael addition occurs onto the double bonds to form crosslinking, while HF is eliminated from crosslinks in the presence of HF scavengers. The crosslinking mechanism with bisphenols takes place also in three main steps (dehydrofluorination, then substitution of a fluorine atom by a bisphenol, and elimination of HF). The most efficient crosslinking bisphenol is bisphenol AF . A fluoropolymer crosslinked with peroxide/coagent systems needs to be functionalized or halogenated to insure a free radical attack from peroxide. The peroxide is introduced with a coagent that enhances the crosslinking efficiency, and the most efficient one is triallylisocyanurate (TAIC). The crosslinking mechanism of the peroxide/triallylisocyanurate system proceeds in three main steps. The crosslinking reaction occurs from a macroradical arising from the functional or halogenated polymer which is added onto the three double bonds of the TAIC. A fourth way to crosslink VDF-based Fluoropolymers deals with high energy radiation, such as X and γ (60Co or 137Cs)-rays, and charged particles (β-particles and electrons). Three different reactions are possible after irradiation of a PVDF, and the one that leads to crosslinking is the recombination between two macroradicals. The irradiation dose used on the VDF-based copolymer has an influence on the thermal and mechanical properties. Finally, a crosslinking system also used to vulcanizate hydrogenated elastomers concerns a thiol-ene system which requires a mercapto function born by the VDF-based polymer. Crosslinking occurs via a non-conjugated diene. The mechanical properties (tensile strength, elongation at break, hardness, elongation modulus, compression set resistance …) of the three main crosslinking systems of fluoroelastomers are compared. Finally, the main applications of crosslinked VDF-based Fluoropolymers are summarized which include tubing in the aircraft building industry, sealing, tube or irregular-profile items of any dimension, films with good adhesion to metallic or rigid surfaces, multilayer insulator systems for electrical conductors, captors, sensors, and detectors, and membranes for electrochemical applications.

Bernard Boutevin - One of the best experts on this subject based on the ideXlab platform.

  • Functional Fluoropolymers for fuel cell membranes
    Solid State Ionics, 2005
    Co-Authors: Renaud Souzy, Bernard Boutevin, Gérard Gebel, Philippe Capron
    Abstract:

    Abstract Various routes to synthesise functional Fluoropolymers used in membranes for fuel cell applications are presented. They can be separated into three main families of alternatives. The first concerns the direct radical copolymerisation of fluoroalkenes with fluorinated functional monomers. The latter are either fluorinated vinyl ethers, α,β,β-trifluorostyrenes or trifluorovinyl oxy-aromatic monomers bearing sulfonic or phosphonic acids. The resulting membranes are the well-known Nafion®, Flemion®, Hyflon®, Dow®, Aciplex® or BAM3G®. The second way deals with the chemical modification of hydrogenated polymers (e.g., polyparaphenylenes) with fluorinated sulfonic acid synthons. The third possibility concerns the synthesis of FP-g-poly(M) graft copolymers (where FP and M stand for fluoropolymer and monomer, respectively) obtained by activation (e.g., by irradiation with electrons, γ-rays or ozone) of Fluoropolymers, followed by grafting of the monomers. The most used M is styrene, and a further step of sulfonation was achieved onto FP-g-PS, leading to FP-g-PS sulfonic acid graft copolymers.

  • Crosslinking of vinylidene fluoride-containing Fluoropolymers
    Advances in Polymer Science, 2005
    Co-Authors: Aurélie Taguet, Bruno Ameduri, Bernard Boutevin
    Abstract:

    Fluoropolymers are well-known for their good properties in terms of chemical, thermal and electrical stabilities, inertness to acids, bases, solvents and oils, and high resistance to ageing and oxidation. Polyvinylidene fluoride (PVDF) is useful as a homopolymer endowed with interesting characteristics. It contains a high crystallinity rate, but is base sensitive. In addition, VDF can be co- or terpolymerized with several fluorinated monomers, rendering them suitable as elastomers and various examples of synthesis of VDF-copolymers are also presented. This review also focusses on binary and tertiary systems containing VDF. Several curing systems for these VDF-containing copolymers have been investigated, especially diamines and their derivatives, aromatic polyhydroxy compounds, peroxides with coagents, such as triallylisocyanurate, radiations, and thiol-ene systems. The best vulcanizate properties are obtained by a two-step process. First, the material is press cured at different times and temperatures, then, it is post cured in air or under nitrogen at higher temperature and time, and under atmospheric pressure. Poly(VDF-co-HFP) copolymers can react with primary, secondary or tertiary monoamines, but they are mainly crosslinked by diamines such as hexamethylene diamine (HMDA), their carbamates (HMDA-C), and derivatives. A mechanism of crosslinking is identified by Infrared and 19F NMR spectroscopies, and was evidenced to proceed in three main steps. First, a VDF unit undergoes a dehydrofluorination in the presence of the diamine, then the Michael addition occurs onto the double bonds to form crosslinking, while HF is eliminated from crosslinks in the presence of HF scavengers. The crosslinking mechanism with bisphenols takes place also in three main steps (dehydrofluorination, then substitution of a fluorine atom by a bisphenol, and elimination of HF). The most efficient crosslinking bisphenol is bisphenol AF . A fluoropolymer crosslinked with peroxide/coagent systems needs to be functionalized or halogenated to insure a free radical attack from peroxide. The peroxide is introduced with a coagent that enhances the crosslinking efficiency, and the most efficient one is triallylisocyanurate (TAIC). The crosslinking mechanism of the peroxide/triallylisocyanurate system proceeds in three main steps. The crosslinking reaction occurs from a macroradical arising from the functional or halogenated polymer which is added onto the three double bonds of the TAIC. A fourth way to crosslink VDF-based Fluoropolymers deals with high energy radiation, such as X and γ (60Co or 137Cs)-rays, and charged particles (β-particles and electrons). Three different reactions are possible after irradiation of a PVDF, and the one that leads to crosslinking is the recombination between two macroradicals. The irradiation dose used on the VDF-based copolymer has an influence on the thermal and mechanical properties. Finally, a crosslinking system also used to vulcanizate hydrogenated elastomers concerns a thiol-ene system which requires a mercapto function born by the VDF-based polymer. Crosslinking occurs via a non-conjugated diene. The mechanical properties (tensile strength, elongation at break, hardness, elongation modulus, compression set resistance …) of the three main crosslinking systems of fluoroelastomers are compared. Finally, the main applications of crosslinked VDF-based Fluoropolymers are summarized which include tubing in the aircraft building industry, sealing, tube or irregular-profile items of any dimension, films with good adhesion to metallic or rigid surfaces, multilayer insulator systems for electrical conductors, captors, sensors, and detectors, and membranes for electrochemical applications.

  • well architectured Fluoropolymers synthesis properties and applications
    2004
    Co-Authors: Bruno Ameduri, Bernard Boutevin
    Abstract:

    Chapter 1 : Telomerisation Reactions of Fluorinated Alkenes. Chapter 2 : Synthesis Of Fluorinated Telechelics as Precursors of Well-Defined Fluoropolymers. Chapter 3 : Synthesis, Properties And Applications of Fluorinated Alternating Copolymers. Chapter 4 : Synthesis, Properties, and Applications Of Fluorinated Diblocks, Triblock, and Multiblock Copolymers. Chapter 5 : Synthesis, Properties, and Applications of Fluorinated Graft Copolymers.

  • fluoroelastomers synthesis properties and applications
    Progress in Polymer Science, 2001
    Co-Authors: Bruno Ameduri, Bernard Boutevin, Georgi Kostov
    Abstract:

    Abstract The review seeks to cover recent developments in the area of fluorinated elastomers. It reports that, except for isolated cases, most fluoroelastomers are synthesized by radical co-, ternary or tetrapolymerizations. Hence, after reminding the most known syntheses of fluoroalkenes involved in the preparation of these Fluoropolymers and recent achievements of block, graft and alternating copolymers, several academic laws and concepts (e.g. kinetics) of the copolymerization are presented. The section dealing with the synthesis of fluoroelastomers is divided into two parts: the first one covers the preparation of fluorinated copolymers containing tetrafluoroethylene, while the second one extensively describes the preparation of fluoroelastomers based on vinylidene fluoride. This section also points out recent syntheses on novel reactive functional trifluorovinyl or vinyl ether monomers for easy curing of original Fluoropolymers. Then, heteroatom-containing fluoroelastomers are briefly summarized. Various methods of curing are reported in the following section while the next one describes ingredients used in formulations of fluoroelastomeric systems. This review also covers compounding and processing of this class of Fluoropolymers. Finally, a summary of various properties and applications of fluoroelastomers is presented showing how such products resistant to severe conditions are useful in modern industries.

Ananth Dodabalapur - One of the best experts on this subject based on the ideXlab platform.

  • fluoropolymer coatings for improved carbon nanotube transistor device and circuit performance
    Applied Physics Letters, 2014
    Co-Authors: Seonpil Jang, Michael L Geier, Pradyumna L Prabhumirashi, Mark C Hersam, Ananth Dodabalapur
    Abstract:

    We report on the marked improvements in key device characteristics of single walled carbon nanotube (SWCNT) field-effect transistors (FETs) by coating the active semiconductor with a fluoropolymer layer such as poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE). The observed improvements include: (i) A reduction in off-current by about an order of magnitude, (ii) a significant reduction in the variation of threshold voltage, and (iii) a reduction in bias stress-related instability and hysteresis present in device characteristics. These favorable changes in device characteristics also enhance circuit performance and the oscillation amplitude, oscillation frequency, and increase the yield of printed complementary 5-stage ring oscillators. The origins of these improvements are explored by exposing SWCNT FETs to a number of vapor phase polar molecules which produce similar effects on the FET characteristics as the PVDF-TrFE. Coating of the active SWCNT semiconductor layer with a fluoropolymer will be adv...

  • transformation of the electrical characteristics of graphene field effect transistors with fluoropolymer
    ACS Applied Materials & Interfaces, 2013
    Co-Authors: Tae Jun Ha, Deji Akinwande, Sk Fahad Chowdhury, Peter J Rossky, Ananth Dodabalapur
    Abstract:

    We report on the improvement of the electronic characteristics of monolayer graphene field-effect transistors (FETs) by an interacting capping layer of a suitable fluoropolymer. Capping of monolayer graphene FETs with CYTOP improved the on–off current ratio from 5 to 10 as well as increased the field-effect mobility by as much as a factor of 2 compared to plain graphene FETs. Favorable shifts in the Dirac voltage toward zero with shift magnitudes in excess of 60 V are observed. The residual carrier concentration is reduced to ∼2.8 × 1011 cm–2. Removal of the fluoropolymer from graphene FETs results in a return to the initial electronic properties before depositing CYTOP. This suggests that weak, reversible electronic perturbation of graphene by the fluoropolymer favorably tune the electrical characteristics of graphene, and we hypothesize that the origin of this improvement is in the strongly polar nature of the C–F chemical bonds that self-organize upon heat treatment. We demonstrate a general method to ...

T M Lu - One of the best experts on this subject based on the ideXlab platform.

  • deposition of amorphous fluoropolymer thin films by thermolysis of teflon amorphous fluoropolymer
    Applied Physics Letters, 1992
    Co-Authors: T C Nason, J A Moore, T M Lu
    Abstract:

    Thin films (0.3–5 μm) of an amorphous fluoropolymer (AF) derived from the copolymeric material Teflon AF 1600 were deposited on Si (100) wafers by vacuum pyrolysis. Infrared spectroscopy indicated that the composition of the deposited films was similar to the source material. The deposited films were amorphous by x‐ray diffraction. The surface morphology contained micropores which did not extend through films deposited at a low rate. The refractive index was ∼1.2 at 633 nm. Comparisons are made to films derived from ordinary Teflon (also by pyrolysis). The mechanism for the repolymerization of the Teflon AF copolymer at the substrate surface is discussed.

Renu Virmani - One of the best experts on this subject based on the ideXlab platform.

  • acute thrombogenicity of fluoropolymer coated versus biodegradable and polymer free stents
    Eurointervention, 2019
    Co-Authors: Sho Torii, Eduardo Acampado, Stephen D Pacetti, Syed Hossainy, Laura Perkins, Frank D Kolodgie, Qi Cheng, Hiroyoshi Mori, Michael J Lipinski, Renu Virmani
    Abstract:

    AIMS: Durable fluoropolymer-coated everolimus-eluting stents (FP-EES) have shown lower rates of stent thrombosis (ST) versus bare metal stents (BMS) and first-generation bioabsorbable polymer (BP) DES. The aim of the study was to evaluate the specific role of the FP in thromboresistance. METHODS AND RESULTS: A total of 57 stents were assessed in three separate ex vivo swine arteriovenous shunt model experiments (first shunt experiment, custom-made fluoropolymer-coated BMS [FP-only] vs. BMS [n=8 each]; second shunt experiment, FP-EES vs. abluminally coated biodegradable polymer sirolimus-eluting stents [BP-SES] vs. BMS [n=8 each]; and third shunt experiment, FP-EES vs. polymer-free Biolimus A9-coated stents [PF-BCS] vs. BMS [n=6 each]). After one hour of circulation, stents were bisected, and each half was dual-immunostained using a platelet cocktail and a marker for inflammation. Antibody staining was visualised by confocal microscopy. In addition, stents were evaluated by scanning electron microscopy. FP-only stents showed significantly lower platelet adherence compared with BMS (% fluorescence-positive area: FP-only=1.8%, BMS=5.6%, p=0.047) with similar inflammatory cell density. FP-EES also demonstrated the lowest platelet adherence compared with BP-SES (p=0.056), PF-BCS (p=0.013) and BMS (p=0.003) with the significantly lowest inflammatory cell density. CONCLUSIONS: Fluoropolymer coating imparts greater thromboresistance relative to BMS and to polymer-free DES designs, which reflects an unique phenomenon known as fluoropassivation, representing one proposed mechanism for clinically observed low ST rates in FP-EES.

  • tct 486 acute thrombogenicity and inflammation in response to a durable fluoropolymer everolimus eluting stent relative to a durable biolinx polymer zotarolimus eluting stent
    Journal of the American College of Cardiology, 2017
    Co-Authors: Sho Torii, Eduardo Acampado, Stephen D Pacetti, Aloke V Finn, Syed Hossainy, Laura Perkins, Frank D Kolodgie, Qi Cheng, Renu Virmani
    Abstract:

    Clinical data indicate differences in acute thrombosis among different drug-eluting stents (DES), which may relate to properties of DES polymer coatings and stent design. We sought to investigate stent thrombogenicity between a durable fluoropolymer coated DES (Xience Alpine, X-EES, Abbott Vascular