The coefficients of diffusion permeability of methanol through the synthesized polymer film–sulfonated polystyrene composite membranes and a Nafion-115 membrane are measured. For several composite membranes with significantly different transport properties, the values of the diffusion flux of methanol qdiff through these membranes under the conditions of a direct methanol fuel cell (DMFC) at 60°C and a concentration of the feed solution of 1–2 M are calculated. Direct measurements of the crossover current and methanol crossover qCVA in a DMFC based on these membranes are carried out by cyclic voltammetry (CVA). It is found that the values of qCVA are on average by 15

Novel ion-exchange membranes based on a commercial porous polytetrafluoroethylene film and sulfonated polystyrene are synthesized. To form porous polytetrafluoroethylene–polystyrene composites, thermal polymerization of styrene sorbed in the pores of the matrix-film from the monomer solution is used. The use of porous matrix makes it possible effectively obtaining the composites, used as precursors of the ion-exchange membranes. The sulfonating of the porous polytetrafluoroethylene–polystyrene composites forms the membranes with ion-exchange capacity up to 2.8 mmol/g. The composition and ground physicochemical properties of the new proton-conducting composite membranes are investigated. The developed membranes were shown to have good transport properties. The proton conductivity of water-saturated membranes is as high as 0.13 S/cm at room temperature; the hydration number is 30. Comparative tests of the synthesized membranes and the commercial Nafion-115 membrane in a direct methanol fuel cell at 60°C showed the characteristics of the fuel cell with the developed membranes being at least not inferior to those of a Nafion-115-based cell.

Abstract—The thermal polymerization of styrene sorbed from the gas-phase into polymer films of polyvinylidene fluoride (PVDF) is carried out at 110°С. By this method, the “matrix‑polystyrene” composites containing up to 70 wt % polystyrene (PS), which serve as precursors of ion-exchange membranes, are synthesized. Sulfonation of grafted PS produces ion-exchange membranes with the exchange capacitance of 1–2.7 mmol/g and the protonic conductivity reaching 20–200 mS/cm when saturated with water at 25°С. The conductivity values indicate that the nonuniformity of PS distribution over film-matrix cross-section usually encountered when monomer sorbed from the gas phase is polymerized does not exert any noticeable effect on the conduction properties of sulfonated composites. The developed method of preparing composites “polymer matrix‑grafted polystyrene” substantially simplifies the synthesis of the precursor of ion-exchange membranes, decreases the necessary amount of reagents, and considerably enhances the safety of synthesis.

A method for the in situ modification of Nafion perfluorinated proton-conducting membranes with a polyelectrolyte based on sulfonated crosslinked polystyrene has been developed. The method is based on the radical copolymerization of styrene with divinylbenzene in situ in the transport channels of Nafion and subsequent sulfonation. The use of a mixed dimethyl sulfoxide–isopropanol solvent, which provides, on one hand, an effective swelling of the Nafion membrane and, on the other hand, the diffusion of nonpolar monomers into the hydrophilic transport channels of the membrane, makes it possible to obtain samples with a uniform distribution of the polyelectrolyte throughout the membrane thickness. The developed method provides a significant increase in the charge carrier concentration and the proton conductivity of the membranes.

The Pt/C catalysts with similar morphology of active catalytic phase (platinum nanoparticles), which were deposited on the supports with different types of carbon structures (Vulkan XC-72 carbon black, Taunit carbon tubes, and Timrex HSAG-300 carbon support with graphite structure), were fabricated by the method of electrochemical dispersion. The effect of the carbon structure type on the electrocatalytic properties of Pt/C catalysts was studied in their operation in the three-electrode cell and in-service in the membrane-electrode assembly of air-hydrogen solid-polymer fuel cell. The Pt/C catalyst based on the Vulkan XC-72 carbon support showed the best performance. The anisotropic shape of Taunit carbon nanotubes and the microstructure of Timrex HSAG-300 carbon support do not allow us to form a catalytic layer with a large active platinum surface area and a structure, which provides an effective ionic transport and mass exchange near the platinum surface.

Currently, nano-and micron materials are increasingly used in various industries. The unusual properties of nanomaterials are due both to the peculiarities of individual particles, and their collective behavior, depending on the nature of the interaction between the nanoparticles. Structure and dispersion of nanomaterials depends on the method their synthesis. Electrochemical methods of the nanomaterials production provide the high purity of materials. The paper discusses the prospects of production of nano-and micro size materials the based on oxides of metals nickel, tin, copper, aluminum by electrolysis in nonstationary conditions. Under a pulsed alternating current (AC) in neutral and alkaline solutions metals oxidized and dispersed to form both amorphous and crystalline dispersed materials. The possibilities of controlling the structure and size characteristics of oxide materials by changing the conditions of electrolysis (current character, composition of the electrolyte) are discussed.