Nanostructured poly(benzimidazole): from mesoporous networks to nanofibers

Poly(benzimidazole)s (PBIs) are a class of high-performance polymers which have been receiving increasing interest during the last years due to their high potential as constituents of membrane materials in proton-exchange membrane fuel cells (PEMFCs). In addition to the importance of PBI in fuel-cell technology, there are a number of other applications (e.g., catalysis) that make use of the special properties of this material. The scope of this Minireview is to first give a short overview about the use of nanostructured, mesoporous PBI as a proton conductor. Secondly, the use of spirobifluorene derivatives as new monomers, which allow the synthesis of hierarchically structured PBI, is presented. Limitations of traditional synthetic methods will be discussed, and an ionothermal scheme towards PBI will be presented as a versatile tool for the synthesis of plain and spirobifluorene-based PBIs. Finally, the use of electrospinning as a powerful processing technique for PBI will be presented briefly.