Proton-conducting polymer electrolyte membranes based on fluoropolymers incorporating perfluorovinyl ether sulfonic acids and fluoroalkenes Synthesis and characterizations

International audienceThis paper presents the synthesis of new polymer electrolyte membranes based on fluoropolymers incorporating aromatic perfluorovinyl ether sulfonic acids. A novel synthetic route describing the preparation of perfluorovinyl ether monomer containing sulfonic functionalities, 4-[(alpha,beta,beta-trifluorovinyl)oxy]benzene sulfonic acid (TFVOBSA), is reported. The radical (co) and terpolymerization of 4-[(alpha,beta,beta-trifluorovinyl)oxy]benzene sulfonyl chloride (TFVOBSC) with 1,1-difluoroethylene (or vinylidene fluoride, VDF), hexafluoropropene (HFP), and perfluoromethyl vinyl ether (PMVE) is described. The terpolymers of TFVOBSC with VDF and HFP, or VDF and PMVE, were hydrolyzed and led also to original fluorinated terpolymers bearing sulfonic acid aromatic side-group. The terpolymers were characterized by 1H and 19F NMR spectroscopies, SEC, DSC and TGA. Membranes incorporating these functional fluoropolymers were prepared and the electrochemical (IEC, proton conductivity, swelling rates) properties were studied and discussed

Immunogenicity and safety of a quadrivalent high-dose inactivated influenza vaccine compared with a standard-dose quadrivalent influenza vaccine in healthy people aged 60 years or older: a randomized Phase III trial

A quadrivalent high-dose inactivated influenza vaccine (IIV4-HD) is licensed for adults 6565 y of age based on immunogenicity and efficacy studies. However, IIV4-HD has not been evaluated in adults aged 60\u201364 y. This study compared immunogenicity and safety of IIV4-HD with a standard-dose quadrivalent influenza vaccine (IIV4-SD) in adults aged 6560 y. This Phase III, randomized, modified double-blind, active-controlled study enrolled 1,528 participants aged 6560 y, randomized 1:1 to a single injection of IIV4-HD or IIV4-SD. Hemagglutination inhibition (HAI) geometric mean titers (GMTs) were measured at baseline and D 28 and seroconversion assessed. Safety was described for 180 d after vaccination. The primary immunogenicity objective was superiority of IIV4-HD versus IIV4-SD, for all four influenza strains 28 d post vaccination in participants aged 60\u201364 and 6565 y. IIV4-HD induced a superior immune response versus IIV4-SD in terms of GMTs in participants aged 60\u201364 y and those aged 6565 y for all four influenza strains. IIV4-HD induced higher GMTs in those aged 60\u201364 y than those aged 6565 y. Seroconversion rates were higher for IIV4-HD versus IIV4-SD in each age-group for all influenza strains. Both vaccines were well tolerated in participants 6560 y of age, with no safety concerns identified. More solicited reactions were reported with IIV4-HD than with IIV4-SD. IIV4-HD provided superior immunogenicity versus IIV4-SD and was well tolerated in adults aged 6560 y. IIV4-HD is assumed to offer improved protection against influenza compared with IIV4-SD in adults aged 6560 y, as was previously assessed for adults aged 6565 y

Functional fluoropolymers for fuel cell membranes

International audienceVarious routes to synthesize 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 copolymerization of fluoroalkenes with fluorinated functional monomers. The latter are either fluorinated vinyl ethers, a,b,b-trifluorostyrenes or trifluorovinyl oxy aromatic monomers bearing sulfonic or phosphonic acids. The resulting membranes are well-known: Nafionw, Flemionw, Hyflonw, Doww, Aciplexw or BAM3Gw. The second route deals with the chemical modification of hydrogenated polymers (e.g. polyparaphenylenes) with fluorinated sulfonic acid synthons. The third alternative concerns the synthesis of FP-g-poly(M) graft copolymers where FP andMstand for fluoropolymer and monomer, respectively, obtained by activation (e.g. irradiation arising from electrons, g-rays, or ozone) of FP polymers followed by grafting of M monomers. The most used M monomer is styrene, and a further step of sulfonation on FP-g-PS leads to FP-g-PS sulfonic acid graft copolymers. Other processes such as multilayer membranes or the introduction of fillers to prepare organic/inorganic or ‘composite membranes' are reported. The electrochemical properties (ionic exchange capacity, conductivity, swelling-rate or water uptake) of membranes produced from fluoropolymers bearing sulfonic, carboxylic or phosphonic acid are presented and discussed

Synthesis and Characterizations of Novel Proton-Conducting Fluoropolymer Electrolyte Membranes Based on Poly(vinylidene fluoride-ter-hexafluoropropylene-ter-α-trifluoromethacrylic acid) Terpolymers Grafted by Aryl Sulfonic Acids†

International audienceThe synthesis and the characterization of new polymer electrolyte membranes made of fluorinated copolymers based on vinylidene fluoride (VDF) and hexafluoropropylene (HFP) and grafted by aryl sulfonic acids are presented. They were obtained in a three-step process. First, the conventional batch radical terpolymerization of α-trifluoromethacrylic acid (TFMAA), VDF and HFP, initiated by 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane led to original fluorinated functional terpolymers bearing carboxylic acid side groups in fair to good yields (>55%). The microstructure and the thermal properties of these macromolecules were studied. Interestingly, poly[(VDF-alt-TFMAA)-co-HFP)] random terpolymers that contained alternated microblock structures based on VDF and TFMAA units separated by one HFP unit were evidenced by 19F nuclear magnetic resonance (NMR) spectroscopy. That technique also enabled us to assess the termonomer contents. Average molecular weights, glass transition temperatures, and decomposition temperatures (under air), determined by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), ranged between 10 000 and 21 400 g mol−1, from−27 to −18 °C and from 140 to 275 °C, respectively. Indeed, the higher the TFMAA content, the lower the thermostability of the terpolymer that arised from decarboxylation. This degradation could be overcome by the reduction of the carboxylic acid dangling functions into hydroxyl ones. The third step concerned an etherification (Mitsunobu) reaction of such resulting primary hydroxyl groups with 4-sulfonic acid phenol. Both these reactions did not affect the contents of fluorinated termonomeric units as evidenced by 1H, 19F, and 13C NMR characterization. The microstructures, physicochemical, and thermal properties of the grafted materials were evaluated by NMR and infrared spectroscopies, SEC and DSC, and TGA. Membranes incorporating these functional fluoropolymers were processed by casting, and their preliminary electrochemical properties (ionic exchange capacity, proton conductivity, and swelling rates that reached 1.2 mequiv mol−1, 9 mS cm−1, and 58%, respectively) were studied, discussed, and compared to those of Nafion and to other fluorinated aromatic membranes of different architectures

Fluoropolymers and membranes prepared from such polymers, in particular for fuel cells and method for synthesizing such polymers

The synthesis and the characterization of new polymer electrolyte membranes based on fluoropolymers grafted by aryl sulfonic acids is presented. They are obtained in a three step-process. First, the radical terpolymerization of a-trifluoromethylacrylic acid (TFMAA), vinylidene fluoride (VDF) and Hexafluoropropene (HFP) , initiated by 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane led to original fluoropolymers bearing carboxylic acid side functions in good yields. The structure and the properties of the materials were studied. Interestingly, poly((VDF-alt-TFMAA)-co-HFP) terpolymers containing alternation of VDF and TFMAA were produced, the termonomer contents of which, were assessed by 19F NMR spectroscopy. Molar masses and glass transition temperatures were ranging between 10,100 and 21,400, and from –27 to –18 °C, respectively. In a second part, the carboxylic functions of these terpolymers were reduced with AlLiH4 followed by an etherification reaction with the sulfonic phenol. Both these reactions did not modified the contents of termonomers as evidenced by 1H, 19F, 13C NMR. The physico-chemical properties of the grafted materials were investigated by NMR and Infrared spectroscopies, SEC, DSC and TGA and are reported. Membranes incorporating these functional fluoropolymers were prepared and the electrochemical properties (IEC, proton conductivity, swelling rates) were studied, discussed, and compared to those on Nafionâ

Fluoropolymers and membranes prepared from such polymers, in particular for fuel cells and method for synthesizing such polymers

L'invention concerne des polymères fluorés comprenant au moins un motif répétitif de formule (I) : dans laquelle : - les groupes X et Y, identiques ou différents, représentent H ou F ; - le groupe Z représente F ou un groupe alkyle perfluoré ; - le groupe W représente CO2 ; - le groupe Ar représente un groupe divalent comprenant au moins un cycle aromatique carboné éventuellement substitué ; - le groupe Q représente une simple liaison, (CF2)n avec 1 ≤ n ≤ 10, ou C2F4OC2F4 ; - le groupe G représente un groupe échangeur de cations, préférentiellement choisi parmi : • SO2R1, avec R1 représentant OH, F ou Cl ; ou • P(=O) (OR2)2 avec R2 représentant H ou un groupe alkyle éventuellement substitué ;ou • CO2H. et possédant une capacité d'échange ionique supérieure ou égale à 0,5 meq/g polymère Leur procédé de synthèse, les membranes obtenues à partir de ces polymères et les dispositifs de pile à combustible comprenant de telles membranes font également partie de l'invention

Functional fluoropolymers for fuel cell membranes

International audienceVarious 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, a,h,h-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, g-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