Low methanol permeable sulfonated poly(ether imide)/sulfonated multiwalled carbon nanotube membrane for direct methanol fuel cell

Abstract

A novel organic/inorganic composite membrane synthesized with sulfonated multiwalled carbon nanotubes (s-MWNTs) and sulfonated polyetherimide (s-PEI) is prepared for use in a direct methanol fuel cell (DMFC). A solution casting method was used to prepare s-MWNT/s-PEI membranes (SPEI membranes) with various s-MWNT contents. This composite membrane showed not only low methanol crossover and water swelling but also enhanced mechanical properties. The IEC and proton conductivity of SPEI membranes were increased by incrementing their s-MWNT content. This is because the number of sulfonic acid groups (SO 3 À ) increases as s-MWNTs are added. The water uptake of SPEI membranes increased as s-MWNT content was increased due to the hydrogen bonded interaction between sulfonic groups and carboxylic groups in s-MWNTs and water molecules. However, the water uptake of SPEI membranes is remarkably low, compared with Nafion membranes. The methanol permeability of the SPEI membranes (8.8 Â 10 À8 cm 2 s À1 ) in this study was also lower than that of the Nafion membrane. Therefore, SPEI membranes were expected to have potential applications in DMFCs. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: E467-E477, 2012

Synthesis and characterization of sulfonated poly(ether imide) with higher thermal stability and effect on CO2, N2, and O2 permeabilities

“…The second, around 530 °C, was related to the main chain decomposition. It was expected an intermediary stage at temperature range between 200-400 °C attributed to partial desulfonation 11,24 , not observed in Figure 2. TGA studies with Nafion, other sulfonated polymer, confirm that occur desulfonation in this temperature range [25][26][27] .…”

“…On the other hand, sulfonation of an aromatic polymer can be very complex because of its reversibility, and can lead to polymer degradation and to losses in thermal and mechanical stability 2,4 . Furthermore, partial desulfonation is observed at temperature range between 200-400 °C [11,24] . From the analysis of the literature, one can see that, by controlling the reactivity of the sulfonation medium, the PEI sulfonation process has potential to lead to new materials with optimized physicochemical properties for applications previously highlighted.…”

“…Because of its excellent properties-price-processability balance 3 , it has gained importance in a wide variety of applications ranging from membranes 1,2,[4][5][6][7][8] , sensors 9,10 , and as a parent material for synthesis of composites 6,8,11 , ion exchange films (dialysis, electrodialysis, or full cells) 5,11,12 , polymer blends 2,6 , and modified polymers 1,[3][4][5][6][7] .…”

“…This sulfonated aromatic polymer shows good ion diffusivities for use as ion exchange membrane, which is a key component in solid polymer electrolyte for dialysis, electrodialysis, or fuel cell applications 5,11 . Some targets to be achieved in the development of new polymer electrolyte membrane (PEM) for fuel cell applications include 15 : high conductivity above 120 °C; good thermal, mechanical, and chemical stability; acceptable durability.…”