Highly Sulphonated Multiblock‐co‐polymers for Direct Methanol Fuel Cells

Abstract

Multiblock‐co‐polymers with different ion exchange capacities were synthesised by nucleophilic aromatic step‐growth polycondensation of hydrophilic and hydrophobic oligomers. The main focus of this work was to investigate the dependence of oligomer reactivity on molecular weight and how the reaction conditions need to be changed to obtain high‐molecular multiblock‐co‐polymers, consisting of long block segments. Multiblock‐co‐polymers composed of short oligomers could be synthesised under mild reaction conditions. The coupling of longer oligomers required more basic reaction conditions, because the reactive functional end‐groups were shielded by the long oligomeric main chain. The membranes were investigated further in terms of their properties relevant for use as polymer electrolyte membrane in direct methanol fuel cells (DMFCs). The mechanical stability of the acidic polymers was improved through ionical crosslinking with basic polybenzimidazole. A series of membranes was tested in a self‐ and in an air‐breathing DMFC.

Proton conducting ABA triblock copolymers with sulfonated poly(phenylene sulfide sulfone) midblock obtained via copper-free thiol-click chemistry

“…Polymer Chemistry -SO 3 H groups for the H + /Na + exchange 66 in the spherical and cylindrical structures.…”

H+-Conducting Aromatic Multiblock Copolymer and Blend Membranes and Their Application in PEM Electrolysis

“…The multiblock-co-ionomers were prepared in a two-step procedure: first, the hydrophilic and hydrophobic blocks were synthesized separately, followed by the blocks' coupling in the second step, according to [20,38]. In Figure 1, the scheme for the multiblockco-ionomer synthesis is depicted.…”

“…In this contribution, multiblock-co-ionomers of different lengths were synthesized. Ether-bridged multiblock-co-ionomers (MBI) were synthesized from hydrophobic, partially fluorinated, and F-terminated homoblock polymer (PFS) [39] and from hydrophilic, sulfonated OH-terminated homoblock (PKK) according to previous work [23,38]. In this contribution, multiblock-co-ionomers of different lengths were synthesized.…”

“…The acidbase blend membranes have been applied to low- [32] and intermediate temperature H 2 fuel cells [33], perstractive alkene/alkane separation [34], and direct methanol fuel cells (DMFC) [35], as well as in H 2 -depolarized SO 2 electrolysis [36] and redox-flow batteries [37]. Blend membranes composed of aromatic multiblock-co-ionomers and polybenzimidazole were previously applied to DMFC, leading to improved performance compared to PFSAs and pure multiblock-co-ionomers [38]. To the best of our knowledge, multiblock-coionomers and acid-base blend membranes have, so far, not been investigated in PEMWE, which is the goal of this study.…”

Nanocomposite membranes of Nafion and Fe3O4-anchored and Nafion-functionalized multiwalled carbon nanotubes exhibiting high proton conductivity and low methanol permeability for direct methanol fuel cells

“…As a result, the development of new polymeric electrolyte membranes for DMFCs attracts much research attention. [1][2][3][4] Most of the prepared membranes have shown comparable or lower proton conductivities, but much lower methanol permeabilities compared to Nafion membranes. Consequently, the membrane selectivity (the ratio of proton conductivity over methanol permeability) is higher than that of Nafion membranes.…”