High temperature polymer blends fuel cell membrane

Abstract This chapter examines the use of high temperature polymers as membranes, fuel cells and solar cells. Also, it considers the application of such materials for aerospace developments. The methods for characterization and testing of specific high temperature polymer blends for each of these applications are reviewed. 

There have been studies indicating that blends of PBI polymers with pyridine-containing polymers could prove useful in a high-temperature PEM fuel cell. Kallitsis et al. [31] combined commercially supplied w-PBI with an aromatic polyether that contained a pyridine moiety in the main chain (PPyPO) these polymer blends were then soaked in 85% wt PA. Dynamic mechanical analysis of a 75/25 PBl/PPyPO block copolymer showed reasonable mechanical strength and flexibility. The conductivity of this copolymer was not reported, but the conductivity of 85/15 PBI/PPyPO block copolymer was 0.013 S cm at a relatively low PA doping level. Further investigation of these systems is required to prove its utility as a fuel cell membrane. 

Kerres et al., among others, developed the acid-base blend membranes from sulfonated polymers and aminated or other basic polymers [98] and concluded that the protonation of the basic groups is incomplete if the base is too weak [99]. Very recently, Frutsaert et al. [70] synthesized novel polymers for the development of high temperature PEMFC membranes comprising a blend of s-PEEK and a fluorinated copolymer bearing imidazole functions as pendant groups. The extensive work on intermediate temperature fuel cell membranes are well reviewed in Chap. 4 of this book including polybenzimidazole as the basic component and sulfonated and phosphonated ionomers of either nonfluorinated or partially fluorinated backbones as the acidic component. 

Pefkianakis, E. K. Morfopoulou, C. Deimede, V. Kallitsis, J. K., Blends of aromatic polyethers bearing polar pyridine units and their evalnation as high temperature polymer electrolytes, Macromol. Sympos., 219(1), 183-190 (2009). Deng, S. Mays, J. W. Hassan, M. K. Mauritz, K. A., Low cost high temperature fuel cell membranes based on poly(l,3-cyclohexadiene) homopolymers, polymer blends, and block copolymers, the 238th ACS National Meeting, ACS Division of Fuel Chemistry, Washington, DC, 16-20.08.2009. 

Sulfonated PBIs, other sulfonated polymers, and their blends show great potential for use as membranes in high-temperature fuel cells. The synthesis, conductivity, mechanical properties, and performance still require further development, but results so far are promising. Further investigation remains to determine whether these problems can be overcome and useful chemistries developed to meet the needs of high-temperature membranes with performance characteristics comparable to lower-temperature membranes. 

Poly(phthalazinoneethersulfoneketone) (PPESK) is a recent high performance, high temperature resistance polymer, but with high viscosity. However, blends with PEI or PES were found to improve processability and allowed reinforcement with carbon fiber. The blends showed excellent mechanical properties. PPESK was also found to be an excellent basic material for the production of a diversity of membranes with applications ranging from water purification to fuel cell. " ... 

Kallitsis, J. K. Gourdoupi, N., Proton conducting membranes based on polymer blends for use in high temperature PEM fuel cells, /. New Mater. Electrochem. %f., 6(4), 217-222 (2003). 

Hu, I Conrad, O., Proton exchange membrane comprising polymer blends for use in high temperature proton exchange membrane fuel cells, Int. Pat. Appl. WO 2011/035795,31.03.2011, to Ewe-Forschungszentrum Ftlr Energietechnologie E. V. 

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