The synthesis of poly(styrene‐co‐sodium styrene‐p‐carboxylate)

This article describes a technique for the homogeneous lithiation and subsequent carboxylation of high‐molecular‐weight polystyrenes containing up to 14 mol %p‐bromostyrene. Thus, poly(styrene‐co‐p‐bromostyrene)s were reacted in dilute tetrahydrofuran solution with large stoichiometric excesses ofn‐butyllithium with no precipitation of ionomer and subsequently carboxylated with anhydrous carbon dioxide or dry ice. By this technique polystyrenes in which up to 100% of the original bromine groups had been replaced by carboxyl functionalities were obtained.