Self-assembly of multiwall carbon nanotubes on sulfonated poly (arylene ether ketone) as a proton exchange membrane
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Membranes of sulfonated poly (arylene ether ketone) containing carboxyl groups (SPAEK-C) are modified by alternating deposition of oppositely charged polyelectrolytes [carboxyl-functionalized multiwalled carbon nanotubes (C-MWCNTs) and chitosan (CS)] in order to reduce methanol crossover and maintain high proton conductivity in a direct methanol fuel cell (DMFC). Fourier transform infrared spectroscopy confirms that C-MWCNTs and CS are assembled in the multilayers. The morphology of membranes is studied by scanning electron microscopy. The results confirm the presence of thin C-MWCNTs/CS multilayers coated on the SPAEK-C membrane. The SPAEK-C-(C-MWCNTs/CS)n membranes maintain high proton conductivity values up to 0.058 Scm−1 at 25 °C and 0.24 Scm−1 at 80 °C, which are superior to previous layer-by-layer assembled polyelectrolyte systems. Meanwhile, the methanol permeability of these modified membranes is effectively reduced. The selectivity of SPAEK-C-(C-MWCNTs/CS)n is two orders of magnitude greater than that of Nafion® 117, making these modified membranes a good alternative to be used in DMFCs. The thermal stability, water uptake, swelling ratio and proton conductivity of SPAEK-C and SPAEK-C-(C-MWCNTs/CS)n membranes are also investigated.
KeywordsSulfonated poly (arylene ether ketone) Proton exchange membrane Carbon nanotubes Methanol permeability
This work was supported by the National Nature Science Foundation of China (Grant No. 21104022) and Jilin University Basic Research Founding (No: 450060481017).