Functional fluoropolymers for fuel cell membranes

Abstract

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

Incorporation of Functionalized Palladium Nanoparticles within Ultrathin Nafion Films: A Nanostructured Composite for Electrolytic and Redox‐Mediated Hydrogen Evolution

“…The shape of the resulting mercury layer formed on the surface of the gold microdisk was observed using optical microscope (Olympus BH2 microscope, Japan) and was characterized by a height which was half that of the disk radius. The electrochemical stability and the geometry of the amalgam UME were examined by running voltammograms for the reduction of oxygen in aerated solution and Ru(NH 3 ) 6 3þ in deaerated solution [66,67]. Before experiments, the Au/Hg UME was stored in a 0.1 M KNO 3 solution and carefully washed with copious amounts of Milli-Q water.…”

“…[1] Among polymer membranes, Nafion, a perfluorinated ion-exchange polymer containing tetrafluoroethylene and perfluorovinyl ether units, terminated with a -SO 3 H group, is probably the most common polymer electrolyte used in PEFCs and DMFCs because of its good thermal and chemical stability, together with high proton conductivity. [2][3][4][5][6] These properties are further expanded through the ability of Nafion to preconcentrate cationic species, making it possible to host a wide range of entities such as redox mediators [7][8][9][10][11][12][13][14] and nanoparticles [15][16][17][18][19][20] for different types of catalytic applications. [21,22] An important factor limiting the practical development of DMFCs is methanol crossover from the anode to the cathode through the polymer membrane; this causes significant loss of fuel and concomitant poisoning of the catalyst at the cathode side.…”

Membrane electrolysis—History, current status and perspective

“…[37,39]. Under these conditions the current efficiency attains a level higher than 95 % [40]. Whereas the voltage efficiency of the process (equilibrium cell voltage has a value of approx.…”

“…At the present time, different modifications of perfluorinated sulfonated membranes in terms of thickness, equivalent weight, reinforcement and surface modifications are commercially available [40,203]. Membrane thickness is important with respect to the potential ohmic loss on the membrane under current load, which decreases with decreasing membrane thickness.…”

Synthesis of Trifluorostyrene Derivatives by Palladium‐Catalyzed Cross‐Coupling of Lithium Trimethoxy(trifluorovinyl)borate with Aryl Bromides

“…[1] However, they have seen little use in other research fields, such as medicinal chemistry, probably due to the lack of a convenient preparative method. [2] Most previous syntheses of TFS derivatives have involved multistep reaction sequences, often involving unstable reagents or intermediates and suffering from low overall yields.…”