"However, the practical application of the PFSA polymers in large scale is limited to some extent due to the high methanol permeability, low conductivity at high temperature and high costs of these materials . To address all these problems, over the years several classes of copolymers were synthesized as potential PEM materials such as sulfonated poly(arylene ether sulfone)s   , sulfonated poly(ether ether ketone)s    , sulfonated polyimides    , sulfonated poly(benzimidazole)s    and sulfonated polytriazoles   . "
[Show abstract][Hide abstract] ABSTRACT: A series of new fluorinated sulfonated polytriazoles with varying degree of sulfonation was synthesized using the click reaction of a new diazide monomer; 4,4-bis[3-trifluoromethyl-4(4-azidophenoxy)phenyl] biphenyl (QAZ) and 4,4'-diazido-2,2'-stilbenedisulfonic acid disodium salt (DADSDB) with 4,4'-(propane-2,2-diyl)bis((prop-2-ynyloxy)benzene) (BPEBPA). The structures of the polytriazoles were confirmed by FTIR and NMR (H-1, C-13 and F-19) spectroscopy. The polytriazoles exhibit high molecular weights, and good solubility and film forming capabilities, combined with high thermal and chemical stabilities, low water uptake, good dimensional stability and high mechanical properties which makes them interesting materials as proton exchange membranes. TEM images of the polytriazole membranes showed nanophase separated morphology with ionic clusters in the range of 5-65 nm. The proton conductivities of the fluorinated membranes were found in the range of 12-76 mS/cm at 80 degrees C in water. A maximum value of even 112 mS/cm was achieved for the non-fluorinated sample.
[Show abstract][Hide abstract] ABSTRACT: Sulfonated poly(arylene ether)s with high content of phosphine oxide moieties were achieved by polycondensation of bis(4-hydroxyphenyl)phenylphosphine oxide with sulfonated bis(4-fluorodiphenyl)phenyl phosphine oxide and bis(4-fluorophenyl)phenyl phosphine oxide (or decafluorobiphenyl) for the first time. The high content phosphine-oxide moieties are expected to improve the oxidative stability of membranes, while the decafluorobiphenyl units were used to depress the swelling. The studies illustrated that all these membranes exhibited outstanding oxidative stability because of high content phosphine oxide moieties. On the other hand, the membranes with decafluorobiphenyl moieties (sPEPOF) displayed low swelling. This originates from these hydrophobic groups because they facilitated the membranes to form narrow ionic clusters. In summary, the sPEPOF membranes exhibited excellent overall properties. For instance, the sPEPOF membrane with 80% sulfonation degree displayed a proton conductivity of 0.077 S/cm as well as a swelling of 12% at 80°C. It also exhibited outstanding oxidative stability and high thermal stability.
Fuel and Energy Abstracts 01/2011; 389. DOI:10.1016/j.memsci.2011.11.006
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