| 摘要 |
This invention provides a binder for a fuel cell which has high adhesion, low methanol solubility, high methanol permeability and high proton conductivity, a composition for electrode formation, an electrode for a fuel cell, and a fuel cell using them. The binder is particularly suitable for a binder for a direct methanol type fuel cell which requires high proton conductivity. The binder for a fuel cell comprises a block copolymer which comprises a block having a repeating structural unit of a divalent aromatic group that contains a protonic acid group and a block having a repeating structural unit of a divalent aromatic group that does not contain a protonic acid group, and which has a glass transition temperature (Tg) of 180° C. or less. In particular, it is preferable that the block copolymer has an ion exchange group equivalent of from 200 to 1,000 g/mole and a weight retention ratio of 90% or more as measured by immersion in a 64 weight % aqueous methanol solution at 25° C. for 24 hours.
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