Entwicklung von Komposit-Polymermembranen mit funktionalisierten Nanopartikeln für Brennstoffzellen-Anwendungen

In der vorliegenden Arbeit wird die Präparation von Komposit-Polymermembranen mit Siliziumdioxid-Partikeln, die teilweise mit fluoriertem Polyoxadiazol Oligomer (ODF) funktionalisiert wurden, vorgestellt. Die dabei verwendeten Polymere reichen vom quasi-Indurstriestandard Nafion® über Poly(arylenether 1,3,4-oxadiazol) zu fluoriertem Polyoxadiazole Random Copolymer. Die Einbettung funktionalisierter Siliziumdioxid-Partikeln bewirkt eine Verbesserung der physikalisch-chemisch Eigenschaften der Membranen, was ihren Einsatz in Hochtemperatur-PEM Brennstoffzellen ermöglicht.A series of composite membranes were prepared by dispersing fluorinated polyoxadiazole oligomer (ODF)–functionalized silica nanoparticles in Nafion®, poly(arylene ether 1,3,4-oxadiazole) and fluorinated polyoxadiazole random copolymers. Ion exchange capacity, conductivity, water uptake and thickness expansion, thermal stability and morphology of the membranes were characterized. The composite membranes showed improved physicochemical properties compared to the pure polymers, allowing for operation in high temperature PEM fuel cells

Nafion\uae/ODF-silica composite membranes for medium temperature proton exchange membrane fuel cells

A series of composite membranes were prepared by dispersing fluorinated polyoxadiazole oligomer (ODF)-functionalized silica nanoparticles in a Nafion\uae matrix. Both melt-extrusion and solvent casting processes were explored. Ion exchange capacity, conductivity, water uptake and dimensional stability, thermal stability and morphology were characterized. The inclusion of functionalized nanoparticles proved advantageous, mainly due to a physical crosslinking effect and better water retention, with functionalized nanoparticles performing better than the pristine silica particles. For the same filler loading, better nanoparticle dispersion was achieved for solvent-cast membranes, resulting in higher proton conductivity. Filler agglomeration, however, was more severe for solvent-cast membranes at loadings beyond 5\ua0wt.%. The composite membranes showed excellent thermal stability, allowing for operation in medium temperature PEM fuel cells. Fuel cell performance of the composite membranes decreases with decreasing relative humidity, but good performance values are still obtained at 34% RH and 90\ua0\ub0C, with the best results obtained for solvent cast membranes loaded with 10\ua0wt.% ODF-functionalized silica. Hydrogen crossover of the composite membranes is higher than that for pure Nafion\uae membranes, possibly due to porosity resulting from suboptimal particle-matrix compatibility. \ua9 2013 [Author/Employing Institution].Peer reviewed: YesNRC publication: Ye