Phosphoric acid-doped cross-linked porous polybenzimidazole membranes for proton exchange membrane fuel cells

Epoxides cross-linked hexafluoropropylidene polybenzimidazole membranes for application as high temperature proton exchange membranes

“…3. Comparing the IR spectra of F 6 PBI-R 3 membranes with that of F 6 PBI membrane, the band at around 3149 cm À1 , assigned to the stretching vibration of N-H groups in benzimidazole rings, became weaker; meanwhile, the absorption band at around 2875 cm À1 , assigned to the -CH 2 -groups in epoxide units of the cross-linker [24,32], became stronger as the increase in the crosslinking degree of the membranes. Moreover, the peak at 1104 cm À1 attributable to the stretching vibration of C-O groups appeared in the spectra of the cross-linked F 6 PBI membranes [38], which indicated the opening of the epoxide rings during the cross-linking reactions [31,33].…”

“…However, the flexible spacer groups (-C(CF 3 ) 2 -) containing in the main chain of F 6 PBI result in less rigidity of the polymer against the plastification of doped PA, which brings about significant thermoplastic deformation of the membranes at elevated temperatures, such as 130 C [25]. To reinforce the F 6 PBI membrane with high ADLs, crosslinking has been demonstrated as an effective method [21,24,25]. The covalent cross-linking of PBI membranes is normally performed between imidazole groups of PBI and electrophilic cross-linking agents containing two or more active groups.…”

“…Among a number of PBI variants, the polymer containing hexafluoropropylidene groups, termed as F 6 PBI, has high stability towards the attack of radical oxidants and good solubility in the normally used organic solvents comparing with those of the pristine mPBI [21][22][23][24][25]. However, the flexible spacer groups (-C(CF 3 ) 2 -) containing in the main chain of F 6 PBI result in less rigidity of the polymer against the plastification of doped PA, which brings about significant thermoplastic deformation of the membranes at elevated temperatures, such as 130 C [25].…”

“…It is seen that the used macromolecule cross-linkers to the PBIs are aromatic polymers, which profit the PBI maintaining its stability. Compared to macromolecules, the small molecule reagents such as halide [24,29,30] and epoxide [31][32][33] are more frequently used cross-linkers for improvement of the membrane properties. In addition, several other methods were also explored to obtain cross-linked PBI membrane electrolytes, which include free radical polymerization of the side chain of cross-linker (i.e.…”

Pt based catalytic coatings on poly(benzimidazole) micromonoliths for indoor quality control

“…Based on this straightforward route, hybrid macroporous PBI membranes containing ETS-10 titanosilicate type materials functionalized with sulfonic groups have been attempted by our group to promote proton conduction keeping lower the phosphoric acid uptake values [14]. In a step further, cross-linked porous PBI with both outstanding mechanical properties and high proton conductivity have been prepared by Hsu et al [15].…”