A series of homologous statistical polymethacrylate comb copolymers with tail-end 4-(dimethylamino)pyridinium ionic groups were synthesized by partial quaternization of high molar mass poly( 12-bromododecyl methacrylate). The copolymers of lower ion content are found to be biphasic by differential scanning calorimetry, resembling classical ionomers, with a lower glass transition temperature (T-g) that remains constant up to about 20 mol % ion content before increasing and a higher T-g that increases monotonically with ion content. X-ray analysis indicates the presence of a soft phase with an invariant microstructure for all of the copolymers, whereas the hard-phase microstructure, considered to be a disordered partial bilayer in the ionic homopolymer, is characterized by an increasing long period with decreasing ion content. Models to reconcile the various data are proposed, which show how large amounts of nonionic units can be incorporated into the hard-phase microstructure, with the invariant soft-phase microstructure also rationalized. This copolymer series thus bridges ionomer and mesomorphic polysoap characteristics by the presence of two phases whose relative proportions vary with ion content, both of which possess their own (short-range) microstructure that determines the nature of their evolution with copolymer composition.