| abstract |
A block copolymer which has at least one block having an acid radical and at least one block having substantially no acid radical, and in which one of terminal groups of a repeating unit in at least one block among all blocks is oxygen and/or sulfur, and at least one repeating unit of a block having substantially no acid radical contains a halogen atom. The block copolymer provides a polyelectrolytic membrane excellent no only in heat resistance and proton conductivity but in water resistance and chemical stability, and is favorably used as an electrolyte, such as a proton conduction film, in a fuel cell. |