Preparation and characterization of SMA/S-POSS hybrid membranes for direct methanol fuel cell applications

A novel sulfonated polyhedral oligomeric silsesquioxane(S-POSS) monomer was synthesized successfully in this article. S-POSS acted as a donor of sulfonic acid group and reacted with poly(styrene-co-maleic anhydride) (SMA). FT-IR spectroscopy confirmed the modification through introduction of peaks characteristic of ester linkages and carboxylic groups. The SMA/S-POSS hybrid membranes were fabricated from different S-POSS contents. The proton conductivity and methanol permeability of the hybrid membranes were studied with changing S-POSS content from 5wt.% to 30wt.%. It was found that the proton conductivity and the methanol permeability were dependent on the S-POSS content. Both of proton conductivity and methanol permeability properties improve with increasing S-POSS content. The proton conductivities of the hybrid membranes are in the range of 10-3-10-2 S·cm-1, and the range of methanol permeabilities was between 10-8 and 10-7 cm2·s-1. The membranes show good thermal properties characterized by thermogravimetric analysis (TGA).

Preparation and properties of composite membrane of bisphenol A-based sulfonated poly(arylene ether sulfone)and phosphotungstic acid for proton exchange membranes

A series of bi A-SPAES(Ds=0.4)/phosphotungstic acid(PWA/bi A-SPAES)composite membranes with various contents of PWA were prepared and characterized by FT-IR.Scanning electron microscopy(SEM)images indicated the PWA were well dispersed within polymer matrix.These composite membranes were evaluated for proton exchange membranes(PEM)in direct methanol fuel cell(DMFC).These membranes showed good thermal stability.It was found that the water uptake of these membranes increased with the increase of the PWA content in the hybrid membranes.Meanwhile,the introduction of inorganic particles increased both the proton conductivity and the methanol permeability.The proton conductivities of composite membranes were increased from 0.017 S/cm to 0.045 S/cm at 20 ℃ and from 0.054 S/cm to 0.093 S/cm at 100 ℃ with the increase of PWA content from 0 to 50 %.Especially,all the methanol diffusion coefficients(4.20×10-8-1.05×10-7cm2/s)of bi A-SPAES/PWA hybrid membranes are much lower than that of Nafion 117 membrane(2.1×10-6 cm2/s).Bi A-SPAES/PWA hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.

Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and SiO_2

Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .

PREPARATION AND CHARACTERIZATION OF AMIDATED PECTIN BASED POLYMER ELECTROLYTE MEMBRANES

The work presents the synthesis and characterization of amidated pectin(AP) based polymer electrolyte membranes(PEM) crosslinked with glutaraldehyde(GA).The prepared membranes are characterized by Fourier transform infrared spectroscopy(FTIR),organic elemental analysis,X-ray diffraction studies(XRD),thermogravimetric analysis (TGA) and impedance spectroscopy.Mechanical properties of the membranes are evaluated by tensile tests.The degree of amidation(DA),molar and mass reaction yields(Y_M and K_N) are calcu...

Effect of Sulfonation Degree on Performance of Proton Exchange Membranes for Direct Methanol Fuel Cells

A series of proton exchange membranes based on sulfonated polyarylene ether ketones（SPAEKs） was used to study the effect of sulfonation degree on proton conductivity, methanol permeation and performance of direct methanol fuel cells（DMFCs）. Dependences of physical characteristics of the membranes, i. e., proton conductivity, water uptake, swelling ratio, methanol permeability and ion exchange capacity（IEC） were systematically studied. Both methanol permeability and proton conductivity of the SPAEK membrane grow rapidly as the increase in sulfonation degree since methanol molecules and protons share the same transfer channel. However, the methanol permeability plays more important role comparing to proton conductivity. As a result, the SPAEK membrane with a medium sulfonation degree（60%） was found to yield the best performance in a DMFC due to the acquirement of balanced conductivity and methanol permeability.