Described herein are anionic phenylene oligomers and polymers, and devices including these materials. The oligomers and polymers can be prepared in a convenient and well-controlled manner, and can be used in cation exchange membranes. Also described is the controlled synthesis of anionic phenylene monomers and their use in synthesizing anionic oligomers and polymers, with precise control of the position and number of anionic groups.