In one embodiment, a copolymer comprises a sulfonatable segment covalently linked to an un-sulfonatable segment through an organic linking group. The sulfonatable group segment may be sulfonated through direction sulfonation or sulfonation through a spacer molecule. In another embodiment, a copolymer comprises a sulfonated segment and an unsulfonated segment. A membrane electrode assembly and a fuel cell may be produced using the copolymer.