Fluorinated comb co-polymers have a main chain including a semi-rigid hydrophobic fluorinated poly(ether) backbone and comb segments in the form of flexible and monodisperse side chains that are more hydrophilic than the backbone. The side chains may be hydrophilic polymeric chains obtained from "living-type" polymerization, for example polymethacrylates, polyethylene oxides, polystyrenes. Hydrophilic functionality, for example, ionic groups may be selectively introduced onto the side chain post polymerization. The side chain may be sulfonated .alpha.-methyl polystyrene. Such polymers are useful in proton exchange membranes.