Creating the First Unhydrous Perfect Single Proton Conductors: Complete Decoupling of Proton Diffusion in Heterocyle (e.g. Imidazole) and Phosphonic Acid Based Systems

Immobilization of imidazole through long, flexible spacers allows for efficient  imidazole aggregation and formation of a dynamical hydrogen bond network supporting fast diffusion of protonic defects.

H. G. Herz, K. D. Kreuer, J. Maier, G. Scharfenberger, M. F. H. Schuster, and W. H. Meyer 
New fully polymeric proton solvents with high proton mobility 
Electrochimica Acta 48(14–16), 2165–2171 (2003). 
DOI: 10.1016/S0013-4686(03)00200-7

M. Schuster, W. H. Meyer, G. Wegner, H. G. Herz, M. Ise, M. Schuster, K. D. Kreuer, and J. Maier 
Proton mobility in oligomer-bound proton solvents: imidazole immobilization via flexible spacers 
Solid State Ionics 145(1–4), 85–92 (2001). 
DOI: 10.1016/S0167-2738(01)00917-1

K.-D. Kreuer, A. Fuchs, M. Ise, M. Spaeth, and J. Maier 
Imidazole and pyrazole-based proton conducting polymers and liquids 
Electrochimica Acta 43(10–11), 1281–1288 (1998). 
DOI: 10.1016/S0013-4686(97)10031-7

K. D. Kreuer 
On the Development of Proton Conducting Polymer Membranes for Hydrogen and Methanol Fuel Cells 
Journal of Membrane Science 185(1), 29–39 (2001). 
DOI: 10.1016/S0376-7388(00)00632-3

M. F. H. Schuster, W. H. Meyer, M. Schuster, and K. D. Kreuer 
Towards a New Type of Anhydrous Organic Proton Conductor Based on Immobilized Imidazole 
Chemistry of Materials 16, 329–337 (2004). 
DOI: 10.1021/cm021298q

M. Schuster, T. Rager, A. Noda, K. D. Kreuer, and J. Maier 
About the Choice of the Protogenic Group in PEM Separator Materials for Intermediate Temperature, Low Humidity Operation: A Critical Comparison of Sulfonic Acid, Phosphonic Acid and Imidazole Functionalized Model Compounds 
Fuel Cells 5(3), 355–365 (2005). 
DOI: 10.1002/fuce.200400059

H. Steininger, M. Schuster, K. D. Kreuer, and J. Maier 
Intermediate temperature proton conductors based on phosphonic acid functionalized oligosiloxanes 
Solid State Ionics 177(26–32), 2457–2462 (2006). 
DOI: 10.1016/j.ssi.2006.04.005

G. Scharfenberger, W. H. Meyer, G. Wegner, M. Schuster, K.-D. Kreuer, and J. Maier 
Anhydrous Polymeric Proton Conductors Based on Imidazole Functionalized Polysiloxane 
Fuel Cells 6(3–4), 237–250 (2006). 
DOI: 10.1002/fuce.200500210

H. Steininger, M. Schuster, K. D. Kreuer, A. Kaltbeitzel, B. Bingöl, W. H. Meyer, S. Schauff, G. Brunklaus, J. Maier, and H. W. Spiess 
Intermediate temperature proton conductors for PEM fuel cells based on phosphonic acid as protogenic group: A progress report 
Physical Chemistry Chemical Physics 9(15), 1764–1773 (2007). 
DOI: 10.1039/b618686f

T. Rager, M. Schuster, H. Steininger, and K.-D. Kreuer 
Poly(1,3-phenylene-5-phosphonic Acid), a Fully Aromatic Polyelectrolyte with High Ion Exchange Capacity 
Advanced Materials 19(20), 3317–3321 (2007). 
DOI: 10.1002/adma.200602788