BENZIMIDAZOLE EFFECT ON THE PERFORMANCE OF POLYELECTROLYTE MEMBRANES BASED ON

Abstract

It is well known that polybenzimidazole electrolyte membranes do not have water

dependence as nafion® membrane and it could be used at intermediate and higher temperatures

(T>100ºC). Otherwise benzimidazole groups can act promoting próton conduction in sulphonated

membrane improving the polyelectrolyte efficiency. This paper discusses an alternatively use of

heterocycles (benzimidazole and a derivative benzimidazole) as protogenic groups for sulfonated

hydrocarbon resins (SR) and poly(vinyl alcohol) semi-interpenetrated polymer network (SR/PVA)

operating at low temperatures. The PVA, a water soluble polymer, was reticulated with

glutaraldehyde and the membranes modified with benzimidazole compounds were prepared by

casting technique from water solution. The SR/PVA membranes were characterized by water uptake

measurements, FTIR spectroscopy, thermogravimetric analysis (TGA) and the conductivity were

assessed by impedance spectroscopy. The presence of benzimidazole leads to moderate water

uptake and this increased with increasing the heterocycles content and the sulfonic acid

functionalized membrane showed reasonable properties. The polyelectrolyte membranes with 40

and 50% (wt%) of benzimidazole showed the highest conductivity values and the 1,4- Bis(N

benzimidazolyl) butane reduced the membrane conductivity.