Synthesis of sulfonated polybenzimidazoles from functionalized monomers: preparation of ionic conducting membranes

International audienceIn the present work, a new sulfonated tetraamine and the corresponding sulfonated polybenzimidazoles (sPBI) were synthesized. For the sake of detg. the best polymn. conditions, a study involving model compds. was first performed. A strong acid medium was used as polymn. solvent, which allowed to obtain high mol. wt. sPBI. A series of polymers with ion exchange capacity (IEC) ranging from 0 to 2.6 mequiv/g were synthesized using a non-sulfonated tetraamine as a comonomer. The chem. structure of those polymers was confirmed by NMR and Fourier transform IR (FTIR) as well as by titrn. Thermogravimetric anal. (TGA) and viscosity measurement were performed as well. On the other hand, different architectures of the copolymers were prepd., i.e., random, sequenced copolymers, and blends of the homopolymers. The membranes prepd. from the sPBI display low water uptake. The ionic conductivities measured in the hydrated state at room temp. ranged from 10-6 to 4 x 10-4 S cm-