An ionically conductive polymer is a copolymer including first and second polymer segments. The first polymer segments have a hydrophobic character and a high oxygen permeability. The second polymer segments have a hydrophilic character and a low oxygen permeability. The copolymer has an ionic conductivity of at least about 1×10−5 S/cm at any point within a temperature range of from 30° C. to 150° C. and a relative humidity range of from 20% to 100%. The ionically conductive polymer can be used in an electrochemical device such as a fuel cell, for example, used as a binder in an electrode or used to produce a membrane.