IN THIS ARTICLE NANOCOMPOSITE BLENDS OF FULLY Sulfonated poly (ETHER KETONE) (PEK) AND NON-Sulfonated poly (ETHER SULFONE) (PES) WERE PREPARED FROM DUAL ELECTROSPINNING PROCESS. SEPIOLITE AS NANOPARTICLE WAS JUST DISPERSED IN NON-Sulfonated PES MATRIX TO PREVENT BARRIER EFFECTS OF NANOPARTICLES AGAINST PROTON IN THESE PROTON EXCHANGE MEMBRANES. THE SPECIAL PRODUCING TECHNIQUE OF THESE MEMBRANES (USING DUAL ELECTROSPINNING PROCESS AND MELTING JUST NON-Sulfonated SEPIOLITE DISPERSED FIBERS) RESULTED MEMBRANES IN WHICH IONIC PATHS (FIBERS OF FULLY Sulfonated PEK) WERE EMBEDDED IN A SEPIOLITE DISPERSED NON-IONIC MATRIX. THE PRESENCE OF THESE IONIC CHANNELS WAS PROVED BY STAINED TRANSMITTANCE ELECTRON MICROSCOPY (STEM). THE THERMAL AND MECHANICAL PROPERTIES AND ALSO WATER ABSORPTION, DIMENSIONAL STABILITY, AND PROTON CONDUCTIVITY OF THESE HYDROPHILIC/HYDROPHOBIC PHASE SEPARATED MEMBRANES WERE MEASURED AND COMPARED IN DIFFERENT SEPIOLITE AND Sulfonated FIBER CONTENTS.

HYDROGEN BONDING CHARACTERISTICS OF ACID-ACID BLEND MEMBRANES BASED ON THE Sulfonated poly (ETHER ETHER KETONE) (SPEEK) AND Sulfonated poly (ETHER SULFONE) (SPES) WERE INVESTIGATED UNDER DIFFERENT WATER CONTENT CONDITIONS USING MD SIMULATIONS METHODS. SIMULATION RESULTS HAVE SHOWN THAT HYDROGEN BONDING INTERACTIONS WERE FORMED BETWEEN SULFONIC ACID GROUPS OF SPEEK AND SPES WITH WATER MOLECULES AND HYDRONIUM IONS, AND ALSO AMONG WATER MOLECULES AND HYDRONIUM IONS. WITH AN INCREASE IN WATER CONTENT, THE NUMBER OF SULFONIC ACID-WATER HYDROGEN BONDS WAS INCREASED WHILE THAT OF SULFONIC ACID-HYDRONIUM IONS WAS FOUND TO DECREASE. FURTHERMORE, THE CALCULATION OF WATER COORDINATION NUMBER FOR WATER AND HYDRONIUM IONS SUGGESTED THE FORMATION OF HYDROGEN BOND NETWORK INSIDE THE HYDRATED STRUCTURE OF SPEEK-SPES BLEND MEMBRANE.

poly (ARYLENE ETHER SULFONE)S (PESS) ARE KNOWN FOR THEIR EXCELLENT THERMAL AND MECHANICAL PROPERTIES. TWO SERIES OF NOVEL poly (ARYLENE ETHER SULFONE)S WERE PREPARED USING DIRECT COpolyMERIZATION OF 3, 3'-DISulfonated-4, 4'-DICHLORODIPHENYL SULFONE AS SYNTHESIZED Sulfonated DIHALIDE IN COMPANION WITH 4, 4'-DICHLORODIPHENYL SULFONE AS NONSulfonated DIHALIDE MONOMER WITH HYDROQUINONE OR 4, 4'-(4, 4'-SULFONYLBIS-(1, 4-PHENYLENE)BIS(OXY))DIPHENOL) AS DIOL. COpolyMERS WERE SYNTHESIZED WITH CONTROLLED DEGREES OF SULFONATION (40, 50 %). 1H-NMR AND FT-IR SPECTROSCOPY WERE USED FOR CHARACTERIZATION OF PREPARED polyMERS. DYNAMIC MECHANICAL THERMAL ANALYSIS AND THERMOGRAVIMETRIC ANALYSIS WERE APPLIED FOR INVESTIGATION AND COMPARISON OF THEIR PROPERTIES. THE polyMERS SHOWED POTENTIAL APPLICATIONS AS MEMBRANE OF FUEL CELL.

BACKGROUND: IN polyMER ELECTROLYTE FUEL CELL OPERATION, A DECREASE IN THE PROTON CONDUCTIVITY OF THE MEMBRANE AT REDUCED HUMIDITY IS A MAIN CAUSE FOR POOR CELL PERFORMANCE AT HIGH TEMPERATURE. TO ALLEVIATE THE DEHYDRATION OF THE MEMBRANE AT HIGH TEMPERATURE, Sulfonated SILICA NANOPARTICLES (SSN) ARE EMBEDDED IN Sulfonated poly (ETHER ETHER KETONE) (SPEEK) MEMBRANES. AS THE SSN ITSELF IS HIGHLY Sulfonated ON ORGANIC MOIETIES, THE PROTON CONDUCTIVITY OF NANOCOMPOSITE MEMBRANES IS MUCH HIGHER THAN THAT OF THE PRISTINE SPEEK MEMBRANE AND IT REACHES THAT OF NAFION 117 AT A HIGH RELATIVE HUMIDITY (RH) OF 90%. THE PROTON CONDUCTIVITY OF THE COMPOSITE MEMBRANES IS MUCH HIGHER THAN THAT OF PRISTINE SPEEK MEMBRANE (S=5×10-2SCM-1)METHODS: poly (2-ACRYLAMIDO-2-METHYL-1-PROPANE SULFONIC ACID)-GRAFTED SILICA NANOPARTICLES (PAMPS-G-SN) WITH AN AVERAGE DIAMETSER SMALLER THAN 70 NM WERE SYNTHESIZED VIA SURFACE-INITIATED FREE-RADICAL polyMERIZATION OF THE AMPS FROM SURFACE OF THE AMINOPROPYL-FUNCTIONALIZED SILICA NANOPARTICLES [1]. Sulfonated polyETHER ETHER KETONE WAS OBTAINED BY DISSOLVING PEEK IN H2SO4 (10 WT %), AT 60OC, UNDER STIRRING, FOR 6 HOURS, TILL THE OBTAINING OF A DARK ORANGE-RED SPEEK SOLUTION. THEN, THE SOLUTION WAS DROPPED INTO DI WATER SLOWLY, AND THEN THE PRECIPITATES WERE FILTERED AND WASHED WITH DI WATER SEVERAL TIMES AND DRIED AT 80OC FOR 24 H. MEMBRANES CONTAINING DIFFERENT AMOUNTS OF PAMPS-G-SN IN SPEEK WERE CAST FROM DMAC TOGETHER WITH A PURE SPEEK REFERENCE MEMBRANE. THE SAMPLES WERE ACTIVATED IN 5 M H2SO4 AT ROOM TEMPERATURE, THEN RINSED WITH DEIONIZED WATER AND DRIED.RESULT: THE DEGREE OF SULFONATION (DS) WAS EVALUATED BY TITRATION METHOD, ACCORDING TO PUBLISHED PROCEDURES [2]. DS OF SPEEK WAS OBTAINED 80%. PROTON CONDUCTIVITY OF MEMBRANES CONTAINING DIFFERENT NANOPARTICLES WAS MEASURED AT ROOM TEMPERATURE AS A FUNCTION OF NANOPARTICLES CONTENT. CONDUCTIVITY VALUES IN THE MEMBRANES INCREASED WITH INCREASING OF Sulfonated NANOPARTICLES. THIS BEHAVIOR CAN BE ATTRIBUTED TO THE PRESENCE OF PROTON CONDUCTIVE SO3H GROUPS IN MEMBRANES PREPARED WITH Sulfonated SILICA.CONCLUSION: HIGHLY HOMOGENEOUS HYBRID MEMBRANES BASED ON SPEEK WITH A HIGH DEGREE OF SULFONATION (DS=0.8) AND VARIOUS AMOUNTS OF NANOPARTICLES WERE PREPARED BY SOLVENT CASTING METHOD. WATER UPTAKE AND PROTON CONDUCTIVITY OF THE NANOCOMPOSITES WERE INCREASED SIGNIFICANTLY BY INCREASING THE Sulfonated NANOPARTICLES.

IN A FUEL CELL SYSTEM, THE ELECTROCHEMICAL REACTIONS TAKE PLACE AT THE THREE-PHASE BOUNDARY WHERE THE ELECTROLYTE, ELECTROCATALYST LAYER AND GASEOUS FUEL ALL CONTACT TOGETHER IN THE MEA. A HIGH THREE-PHASE BOUNDARY ELECTRODE PROMOTES A GOOD GAS AND WATER DIFFUSION, PROTON TRANSPORT AND ELECTRON TRANSPORT TO AND FROM THE CATALYTIC SITES. THE QUALITY OF THE THREE-PHASE BOUNDARY DEPENDS SIGNIFICANTLY ON THE FABRICATION PROCEDURE OF THE MEA, IN ADDITION TO OTHER IMPORTANT PARAMETERS, SUCH AS THE ELECTROCATALYST LOADING AND IONOMER LOADING. AS A KEY COMPONENT OF ELECTRODE, THE ELECTRODE IONOMER FORMS THE IONOMER NETWORK IN THE CATALYST LAYER AND ACTS AS A PROTON CONDUCTING MEDIUM. IN ADDITION, SINCE THE ELECTRODE IONOMER CAUSES CHANGE OF THE PORE STRUCTURE IN THE CATALYST LAYER, IT HAS A GREAT INFLUENCE ON CATALYST UTILIZATION AND GAS TRANSFER TO THE CATALYST. Sulfonated poly ETHER-ETHER KETONE (SPEEK) HAS A POTENTIAL FOR PROTON EXCHANGE FUEL CELL APPLICATIONS. IN THIS STUDY SPEEK WAS PREPARED BY THE SULFONATION OF PEEK. THE DEGREE OF SULFONATION WAS DETERMINED 65% BY H-NMR. THE RESULTS SHOWED THAT IN 25 WEIGHT PERCENT OF SPEEK IONOMER IN THE CATALYST LAYER, PLATINUM UTILIZATION AND ELECTROCHEMICAL ACTIVE SURFACE ARE MAXIMUM.

NOVEL poly (ARYLENE ETHER SULFONE) S WERE PREPARED USING DIRECT COpolyMERIZATION OF 3, 3' -DISulfonated- 4, 4' -DICHLORODIPHENYL SULFONE AS SYNTHESIZED Sulfonated DIHALIDE IN COMPANION WITH 4, 4' -DICHLORODIPHENYL SULFONE AS NONSulfonated DIHALIDE MONOMER WITH 2, 7-NAPHTALENE DIOL. COpolyMERS WERE SYNTHESIZED WITH CONTROLLED DEGREES OF SULFONATION (40, 50 %). 1H-NMR AND FT-IR SPECTROSCOPY WERE USED FOR CHARACTERIZATION OF PREPARED polyMERS. DYNAMIC MECHANICAL THERMAL ANALYSIS AND THERMOGRAVIMETRIC ANALYSIS WERE APPLIED FOR INVESTIGATION AND COMPARISON OF THEIR PROPERTIES. COpolyMERS SHOWED ACCEPTABLE PROPERTIES AS PROTON EXCHANGE MEMBRANE FOR FUEL CELLS. ION EXCHANGE CAPACITY OF MEMBRANES WAS BETWEEN 0.74 AND 1.47 MEQ/G. MEMBRANES SHOWED PROTON CONDUCTIVITIES INCREASED BY INCREASING IN DEGREE OF SULFONATION AND REACHED TO 0.07 S/CM. THE polyMERS SHOWED POTENTIAL APPLICATIONS AS MEMBRANE OF FUEL CELL.

MOLECULAR DYNAMICS (MD) SIMULATION TECHNIQUE WAS USED TO INVESTIGATE THE EFFECT OF DEGREE OF SULFONATION (DS) ON THE STRUCTURAL AND TRANSPORT PROPERTIES OF Sulfonated poly (ETHER ETHER KETONE) (SPEEK) MEMBRANE AT DIFFERENT TEMPERATURES. SIMULATIONS WERE PERFORMED FOR THE CELL CONTAINING SPEEK MEMBRANE, HYDRONIUM IONS AND WATER MOLECULES. BY ANALYZING THE PAIR CORRELATION FUNCTION (PCF), IT WAS FOUND THAT WITH INCREASING THE DEGREE OF SULFONATION, THE DISTANCE BETWEEN SULFONIC ACID GROUPS AND THE DISTANCE BETWEEN SULFONIC ACID GROUPS AND HYDRONIUM IONS ARE DECREASED. FURTHERMORE, THE PCF ANALYSIS OF WATER-HYDRONIUM PAIR SHOWS THAT WATER MOLECULES AND HYDRONIUM IONS ARE LOCATED AT FAR DISTANCES FROM EACH OTHER. HOWEVER, THE DIFFUSION COEFFICIENT AND IONIC CONDUCTIVITY OF HYDRONIUM IONS INCREASE DUE TO THE GREATER NUMBER OF THE HYDRONIUM IONS AT HIGH DS CONDITIONS. SIMULATED IONIC CONDUCTIVITIES FOLLOW EXPERIMENTAL DATA QUALITATIVELY, BUT DUE TO SIMULATION CONDITIONS, SOME DIFFERENCES BETWEEN SIMULATION RESULTS AND EXPERIMENT ARE OBSERVED.

MEMBRANE DURABILITY IS A KEY PROBLEM TO THE DEVELOPMENT OF PROTON EXCHANGE MEMBRANE FUEL CELLS. THE AROMATIC BASED MEMBRANES POSSESS A GOOD MECHANICAL PROPERTIES, THERMAL AND CHEMICAL STABILITY. A NEW CATALYST WAS PREPARED TO MITIGATE THE FREE RADICAL ATTACK THROUGH THE MEMBRANES AND REDUCE THE DEGRADATION OF THESE MEMBRANES IN FUEL CELL ENVIRONMENT. WE HAVE PREPARD NANOCOMPOSITE MEMBRANES BASED ON Sulfonated poly (ETHER ETHER KETONE) AND HETEROpolyACID SUPPORTED PT CATALYST FOR FUEL CELL APPLICATIONS. CESIUM SALT SUPPORTED PT CATALYST WAS SYNTHESIZED BY A TITRATION METHOD AS DECRIBED IN LITERATURE. IN THE PRESENT STUDY, THE SELF-HUMIDIFYING NANOCOMPOSITE MEMBRANES AND THEIR CHEMICAL STABILITY HAS BEEN INVESTIGATED. THE CRYSTALLINE STRUCTURE AND SIZE WAS CHARACTERIZED BY X-RAY POWDER DIFFRACTION (XRD) AND THE AMOUNT OF PT PARTILCES ON THE NANOCOMPOSITE CATALYSTS WERE INVESTIGATED BY XRF ANALYSIS. ALSO, THE MEMBRANES’ CHEMICAL STABILITY WAS STUDIED VIA EX-SITU FENTON TEST. FROM FENTON’S TESTS, THE CHEMICAL STABILITY OF MEMBRANES DECREASED BY INCREASING THE AMOUNT OF PT CATALYSTS.