Preparation, characterization and fuel cell application of new acid-base blend membranes

In our contribution we present the preparation and characterization results of different types of acid-base ionomer blends. As acidic blend components sulfonated polyetherketone and sulfonated polysulfone have been applied, w hile as basic components PSU(NH2)(2), poly(4-vinylpyridine), and polybenzim idazole have been used. The thermal stabilities of the observed blend membr anes ranged from 270 to 350 degrees C. Membranes showing low ionic resistan ces of <50 Ohm.cm were prepared. Some of the acid-base blend membranes were investigated in electronmicroscopy (TEM and SEM). The TEM micrographs show ed a fine structure in the Angstrom size range, and at some of the membrane s also structures in the 50-200 nm size range were observed. The FTIR analy sis of the acid-base blends showed characteristic bands indicating ionic cr osslink formation in the blends. Some of the membranes were applied to fuel cells. These membranes showed good performance both in H-2 and direct meth anol fuel cells. The experiments yielded the result that the electrical pow er which is obtained with these membranes is comparable with the power obta ined with Nafion(R) if the ion-exchange capacity of the membrane is high en ough and if its thickness is in the range of 30-40 cm(2) The maximum power densitiy achieved with one of the acid-base membranes in a direct methanol fuel cell amounted to approximately 50 mW/cm(2) at 100 mA/cm(2) in air mode , which is a value comparable to that obtainable with Nafion(R).