Silicon-containing sulfonated polystyrene/acrylate-phosphotungstic acid hybrid membranes with high methanol barrier and good proton conductivity

In this paper, the silicon-containing sulfonated polystyrene/acrylate-phosphotungstic acid (Si-sPS/A-PWA) hybrid membranes are prepared to obtain the inexpensive proton exchange membrane (PEM) materials that can be fabricated simply with high methanol barrier and good proton conductivity. The Si-sPS/A-PWA hybrid membranes are characterized as the function of PWA to evaluate their potential as PEMs in direct methanol fuel cells (DMFCs). FTIR spectra prove the interaction between Si-sPS/A and PWA molecules and the existence of crosslinked silica network structure in hybrid membranes. All the hybrid membranes exhibit good thermal stability, reasonable water uptake and excellent hydrolytic stability. Most importantly, the hybrid membranes possess higher proton conductivity in the case of keeping low methanol diffusion coefficient compared with the pure Si-sPS/A membrane. The selectivity values of hybrid membranes increase with increasing PWA content and Si-sPS/A-PWA 15 membrane shows the best selectivity (9.79 x 10(5) Ss cm(-3)) which is approximately 5.9 times of that (1.65 x 10(5) Ss cm(-3)) of pure membrane. These results suggest that the Si-sPS/A-PWA hybrid membranes are possible candidate materials for PEMs in DMFC applications. (C) 2010 Elsevier B.V. All rights reserved.