Alginic acid–imidazole composite material as anhydrous proton conducting membrane

Recently, membranes with high anhydrous proton conducting have been attracted remarkable interest for the application to the polymer electrolyte membrane fuel cell (PEFC). In this paper, we have investigated the anhydrous proton conductor consisting of alginic acid (AA), one of the acidic biopolymers, and imidazole (Im). This AA–Im composite material showed the proton conductivity of 2×10−3 S cm−1 at 130 °C under anhydrous conditions. Additionally, these AA–Im composite materials have the highly mechanical property and thermal stability. Furthermore, the biological products, such as biopolymer, are cheap, non-hazardous, and environmentally benign. The proton conductive biopolymer composite material may have the potential for its superior ion conducting properties, in particular, under anhydrous (water-free) or extremely low humidity conditions.