Proton conductive nano-channel membranes based on polyaniline with phosphonic acid moieties for low relative humidity.

Most sulfonic acid based-membranes come to the limit because of high cost and low performance at low relative humidity (RH). Therefore, we synthesized phosphonic acid functionalized polyaniline (PA-PANI). PANI was used as polymer back bone because of excellent chemical mechanical stability and easy synthesis from relatively cheap monomer, and phosphonic acid presents the relatively high proton conducting in nano-channel without water because of its self dissociation nature. PA-PANI was synthesized by bonding chemically with phosphonic acid groups using 3-bromopropylamine as a reagent. PA-PANI nano-channel membrane showed high and stable conductivities (approximately 0.035 S/cm at 80 to approximately 180 degrees C) under low RH. And PA-PANI nano-channel membranes compared with Nafion (10(-4) S/cm at < 30% RH), have higher proton conductivities. This fact showed phosphonic acid groups were more effective at low RH than sulfonic acid groups. Because the proton conductivity of Nafion decreases considerably at elevated temperature due to dehydration, our low cost membranes using phosphonic acid moiety may be expected to substitute sulfonic acid based-membranes such as Nafion.

Characterization of sulfonated poly(ether ether ketone)/silane nanocomposite membrane for high temperature polymer electrolyte membrane fuel cells.

The perfluorosulfonic acid polymer membrane is most widely used in PEMFCs. However, its some major drawbacks like high cost and performance limitation at high temperature are obstacles of its commercialization. The goal of this study was to develop low cost membranes which have good conductivity in the range of PEMFCs operating temperature. We fabricated new sPEEK/3-APTES nanocomposite membrane where inorganic particles were chemically bonded to sulfuric acid group of sPEEK. PEEK is a thermally stable, mechanically tough and very cheap polymer. And the addition of 3-APTES and phosphorous acid increased the proton conductivity of composite membranes at high temperatures. This nanocomposite membranes maintained good conductivity at 110 degrees C.

Poly(dimethyl siloxane) membrane for high temperature proton exchange membrane fuel cells.

Sulfonic acid-based membrane gives the relatively high conductivity only in the presence of water, but phosphoric acid presents the relatively high proton conductivity without water because of its self dissociation natures to develop high temperature PEMFCs. We synthesized the thermostable material that has phosphorous groups based on poly(dimethyl siloxane) (PDMS). PDMS, which is intrinsically hydrophobic was modified to be amphiphilic by substituting end groups with hydrophilic phosphorous groups. Phase separation resulted in forming the proton conducting channels. The membranes maintained the constant proton conductivity above 130 degrees C under dry conditions. Also they were thermally stable up to 300 degrees C and may be used as high temperature proton conducting membrane at low humid conditions.