Electrochimica Acta, Vol.144, 168-173, 2014
Polypeptide for anhydrous proton conductor
The anhydrous proton conductor consisting of a polypeptide was prepared by the mixing of polyglutamic acid (poly(Glu)) and polyhistidine (poly(His)), which were synthesized by the polymerization of an amino acid with diphenylphosphoryl azide (DPPA). These polypeptide hybrid materials interacted between the carboxyl group of poly(Glu) and the imidazole group of poly(His) and produced the acid-base structure. As a result, these polypeptide hybrid materials showed a thermal stability at intermediate temperatures (<= 200 degrees C). Additionally, these hybrid materials indicated the proton conductivity of 1.4 x 10(-4) S cm(-1) at 180 degrees C under anhydrous conditions. Furthermore, an activation energy of the proton conduction under anhydrous condition was 0.52-0.63 eV, one order higher than that of the customary humidified perfluorinated membranes. These results suggested that the proton transfer of hybrid material occurred by the anhydrous proton conductive mechanism. Therefore, the polypeptide hybrid material may have the potential to be utilized as a novel proton conductor under anhydrous condition. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords:Anhydrous proton conduction;polypeptide;polymer electrolyte membrane;histidine;glutamic acid