In Chapter 1 research of hydrogen/air and direct methanol fuel cell membranes especially on the synthesis of new proton conducting membranes is reviewed. Alternative polymer electrolyte membranes such as modified Nafions, polyimides, polyarylene ethers, acid-base polymer blends and polyphosphazenes have been compared to the currently used perfluorinated polymer electrolytes such as Nafions. Because polyphosphazenes are another subject that is involved in the fuel cell research. They are also discussed herein including applications as fuel cell membranes.
Chapter 2 and Chapter 3 focus on the syntheses and characterizations of phosphazene cyclic trimers and linear polymers. The nucleophilic substitution reactions of both phosphazenes with azolylphenol derivatives are discussed. Along with “click” chemistry, a secondary reaction of phosphazene compounds then generates a new route to obtain novel phosphazene compounds. An amino-end compound, such as hexaaminopheoxy-substituted cyclotriphosphazene, is also synthesized by a two-step reaction. Characterization techniques such as nuclear magnetic resonance, mass spectrometry, elemental analysis, infra-red spectrometry and single-crystal X-ray diffraction are applied. The thermal properties of these compounds are examined by thermogravimetric analysis and differential scanning calorimetry.
Chapter 4 and Chapter 5 focus on a membrane preparation and characterization. Chapter 4 is a preliminary study of a triazole-based copolyimide. The preparation and characterization of phosphazene-based proton conducting membranes are discussed in Chapter 5. The conducting membranes are acid-doped composites between a triazole-based copolyimide and the selected phosphazene compound. Basic properties such as water uptake and acid doping levels along with their thermal properties and proton conductivity are discussed.