Polybenzimidazole-graft-polyvinylphosphonic acid-proton conducting fuel cell membranes

• Published in: Journal of applied polymer science 2013-08, Vol.129 (3), p.1223-1231
• Main Authors: Sinigersky, Vesselin, Budurova, Dessislava, Penchev, Hristo, Ublekov, Filip, Radev, Ivan
• Format: Article
• Language: English
• Subjects: Applied sciences; batteries and fuel cells; conducting polymers; Conduction; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; Fuel cells; Grafting; Materials science; Membranes; Phosphonic acids; Polybenzimidazoles; Polymer industry, paints, wood; Polymers; Relative humidity; Reproduction; Synthesis; Technology of polymers
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.38780

A new method for the preparation of polybenzimidazole (PBI)‐based membranes, containing high concentrations of immobilized phosphonic acid groups, has been developed. The procedure used is carried out in two steps: (1) Synthesis of modified PBIs, containing 1,2‐dihydroxypropyl groups and preparation of films there from; (2) Introduction of vinylphosphonic acid (VPA) and initiator (cerium ammonium nitrate) in the film, subsequent grafting of VPA from the active sites of the PBI backbone. Membranes with different length of the grafted polyvinylphosphonic acid chains were prepared. The molar ratio grafted VPA units per PBI repeating unit reaches 7.8. Proton conductivity was measured at 120°C and relative humidity (RH) 20–100%. For the membrane with highest concentration of phosphonic acid groups the proton conductivity was 35 mS cm−1 at 100% RH and 8 mS cm−1 at 20% RH. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013