Dodecaboratclusterhaltige Membranen für Brennstoffzellen

Abstract

In this work it was to be shown whether dodecaborate cluster-containing polymers can have possible applications as polymer electrolyte membranes in fuel cells. There are two possibilities to prepare membranes containing dodecahydro-closo-dodecaborate (2-). On the one hand by polymerization of boron cluster-containing monomers to linear, branched or cross-linked polymers. Or on the other hand by substitution of existing membranes such as Nafion with the B12-cluster. It was possible to synthesize a variety of monomers with a [B12H11]2- moiety, which some could be polymerized successfully. Radical homo-, co- and photo polymerizations were not successful with boron cluster monomers. Only the photo polymerization of the acrylic acid derivative in the NMR experiment was successful, which might be due to the used Spot Lamps. Cationic polymerizations were also not successful. Also hydrosilylations were no suitable polymerizations for boron cluster-containing monomers. Polycondensation reactions with B12H11 monomers were promising. The reaction of dihydroxybenzylammonioundecahydro-closo-dodecaborate with decafluorobiphenyl showed no starting material in the MS, instead it shows a triply negatively charged peak with a yet unknown structure. With the ring-opening metathesis polymerization bis-norbornene derivatives of the dodecaborate cluster could not be polymerized. However, the mono norbornene derivatives of B12H12(2-) formed insoluble swelling polymers in the homo- and copolymerization with dicyclopentadiene and Grubbs 2nd Generation catalysts. Another method to produce a boron cluster-containing polymer is the substitution of Nafion with the boron cluster. From the obtained polymers, films can be produced, which, however, have no better thermal stability than the pure Nafion membrane. However, investigations whether they are suitable as a membrane material must still be carried out.