Benzimidazole-containing sulfonated

Benzimidazole-containing sulfonated polyimides, (IV), prepared by Bmnelle [4] were effective as proton exchange membranes for fuel cells. 

Qi, Y. H., Gao, Y, Tian, S. H., Hill, A. R., Gaudet, J., etal. (2009), Synthesis and properties of novel benzimidazole-containing sulfonated polyethersulfones for fuel cell applications. Journal of Polymer Science Part A-Polymer Chemistry, 47,1920-29. 

Pyridine-containing polymers can also be synthesized using the eondensation polymerization method. For example, a novel series of benzimidazole-containing sidfonated polyaiylene sulfones with a controllable amonnt of basic... 

Soluble, containing sulfonic acid benzimidazole (SPBI) Sulfonated poly(ether ether ketone) (SPEEK) Dimensional stability in water at 80 C). Proton conductivity and lEC = 55 mS/cm 2010 57... 

Poly(arylene ether benzimidazole)s have received more attention than any other PAE containing heterocyclic units. This is due primarily to their unique combination of properties even at relatively low molecular weights and their potential for use in several high performance applications. The initial report in 1991 involved polymers from the reaction of 3 different bis[(4-hydroxy-phenyl)benzimidazole]s with various activated aromatic difluoro monomers as shown in Eq. (10) [37]. The bis[(4-hydroxyphenyl)benzimidazole]s were prepared from the reaction of aromatic bis(o-diamines) and phenyl-4-hydroxybenzoate in diphenyl sulfone. The use of 4-hydroxybenzoic acid would obviously reduce the... 

A-Phosphorylated imidazoles and benzimidazoles can be made by direct phosphorylation by halides, esters, amides, amidoesters, isocyanates, and thiocyanates of phosphorus-containing acids, or from reaction of phosphonic or phosphinic imidazolides with a sulfonic acid or anhydride <82CB1636>. Stable charge transfer complexes are produced when a 1 1 or 1 2 ratio of imidazole (or benzimidazole) and sulfur trioxide are refluxed in ether, dioxane, THE, or 1,2-dichloroethane. These complexes are stable on storage in the absence of water and have sharp melting points. Indeed, the benzimidazole SO3 complex must be boiled for five hours in water to decompose it. On fusion, the complexes form the C-sulfonic acids (see Section 3.02.5.3.3) <87CHE1084>. Sulfonyl chlorides readily A-sulfonate imidazoles <94JMC332>. 

Aryl sulfones are synthesized from RS02Na and Ar B(OH)2 under oxidative conditions (DMSO, O2). Two similar procedures, both using Cu(OAc)2 as catalyst but different A-heterocycle addends, have been established. A-Cyclopropylation of indole is accompUshed, also by following a similar recipe, with the necessary changing the coupling partner to cyclopropylboronic acid. CycUzation of A-arylamidines to afford benzimidazoles involves activation of the o-C—H bond in a process realized by the action of Cu(OAc)2 in DMSO (containing 2.5 equiv. HOAc) under O2 at 100°. ... 

Polybenzimidazoles are synthesized from aromatic tetraamines (bis-o-diamines) and dicarboxylates (acids, esters or amides). Generalized monomers are shown in FIGURE 1 and polybenzimidazoles from those monomers are shown in FIGURE 2. In either figure, R(l) and R(2) can be aromatic or aliphatic and may contain other groups as ether, ketone, sulfone, etc. The structures shown do not exhaust all possible benzimidazole polymers. 

A-heterocycles like imidazole as proton solvents were used to replace water in Nafion and found to significantly improve the proton conductivity of these membranes under anhydrous conditions at elevated temperatures. Stm et al. [90] were among the first workers to prepare the water-free Nafion membranes by swelling them in imidazole and imidazolium salt solutions (e.g., trifluoroacetate and trifluor-omethane sulfonate). Yang et al. [91] reported that a recast Nafion membrane containing 10 wt % imidazole exhibited a conductivity of as high as 0.1 S cm at 160-180 °C. On the other hand, soaking Nafion membranes in either molten imidazole [91] or imidazole solutions in methanol [91, 92] led to much lower cmiductivities of 10 S cm IH-1,2,4-triazole [93, 94], benzimidazole [93], 3-amino-1,2,4-triazole [94], and 5-aminotetrazole [94] have also been explored. These efforts are summarized in Table 3.1. 

Block copolymers combing PBI with other types of macromolecular units have also been developed for superior membrane properties, as shown in Fig. 7.6. Two types of copolymers have been prepared, characterized, and evaluated as fuel cell electrolytes. One is the sulfcmated copolymer containing PBI and snUrmated polymer moieties for low temperature PEMs in both PEM fuel cells and direct methanol fuel cells (DMFCs) [123-126]. The other is the random copolymer containing PBI and poly(imine/ amide) moieties [127, 128]. For the sulfonated PBI copolymers, benzimidazole monomers... 

High-molecular/low-molecular composites such as blends of poly (benzimidazoles) with phosphoric acid as the proton-conducting component or phosphoric acid blended into other organopolymers [24-27], or blends of a sulfonated polymer with amphoterics such as imidazoles or pyrazoles or imidazole-containing oligomers or polymers alone [28,29], or blends of sulfonated polymers with heteropolyacids [30-32]. 

---