| NafionRTM is a polymer membrane widely used in polymer electrolyte membrane fuel cells (PEMFC). It was found that aluminum countercations exchanged into NafionRTM-117 can result in a catalytic decomposition of the perfluoroalkylether (PFAE) side chains of the NafionRTM. The surface morphology of NafionRTM-117 membranes treated with amine-terminated polyamidoamine (PAMAM) generation 4 (G4) and generation 0 (G0) dendrimers were studied. The results proved the interaction between the sulfonic acid groups in NafionRTM-117 and the amino groups in the PAMAM dendrimers. They also indicated the presence of the PAMAM G4 and G0 dendrimers at different positions in NafionRTM-117 after treatment. Their different positions in NafionRTM-117 resulted in different influences on the orientation and distribution of the sulfonate clusters in NafionRTM-117, which in turn affect its transport properties.; The accelerating rate calorimeter (ARCRTM) is an instrument for hazards evaluation of reactive chemicals. A modification was made to the commercial ARCRTM, which has allowed for gaseous samples to be tested without the introduction of air. Four poly-HFPO derivatives: K6-EF, K6-IPA, K6-HEC, and K7-CF(CF3)CH2F, were tested in the modified ARCRTM. Under oxygen atmosphere, K6-IPA was stable up to 420°C; K6-EF and K6-HEC began to decompose at ca. 370 and 308°C, respectively. AlF3 can largely decrease their thermal stability even under vacuum. It was found that prior to thermal decomposition, the AlF3 attached to poly-HFPO chains to form a complex through an endothermic process. After that, when the temperature was increased to ca. 200°C, AlF3 began to catalyze the chain decomposition. When hydrogen is present in the end groups, C2F5H can be produced, which reacts with AlF3, thereby reducing its activity. Five ionic liquids [3-H-1,2-MMIM][NO3], [3-HMIM][NO3], [3-HBIM][NO3], [BMIM][NO3], and [BMIM][Cl] were also tested in the modified ARCRTM under an oxygen atmosphere. The results showed that the disubstituted imidazolium cations were much more stable than the monosubstituted imidazolium cations. A substituent group with a low positive inductive effect is more suitable for the formation of an energetic ionic liquid. It was also found that the nitrate anion, when compared to the chloride anion, could promote the decomposition reaction, especially in the absence of oxygen. |
