Triblock copolymer ionomer membranes Part I. Methanol and proton transport
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In this study, the transport properties (i.e. methanol and proton transport) of a triblock copolymer ionomer, sulfonated poly(styrene-isobutylene-styrene) (S-SIBS), at various ion contents were investigated for its application to the direct methanol fuel cell (DMFC). Methanol permeabilities in S-SIBS were more than an order of magnitude lower than Nafion 117, but conductivities were only three-fold less at ambient conditions. S-SIBS was approximately 5-10 times more selective (i.e. proton conductivity/methanol permeability) than Nafion 117 over an ion content range of 0.5-1.0mmol/g. Also, the transport results follow a power law dependent percolation model, where the critical exponent for diffusion was much lower than those reported in other studies, suggesting a more ordered nanostructure. In addition, transport at higher temperatures (80°C) was examined. At 80°C, S-SIBS was only 1.3 times more selective than Nafion 117 at an ion content of 1.0mmol/g, but was 39 times more selective at an ion content of 0.5mmol/g. © 2003 Elsevier Science B.V. All rights reserved.
author list (cited authors)
Elabd, Y. A., Napadensky, E., Sloan, J. M., Crawford, D. M., & Walker, C. W.