p‐carboxylation of linear high molecular‐mass polystyrene

A simple method is reported for the post‐polymerization partial p‐carboxylation of linear polystyrene without degradation or crosslinking of the polymer. The method is based on Friedel–Crafts acetylation of the polystyrene under mild conditions, followed by oxidation of the acetyl groups by means of a phase‐transfer‐catalyzed haloform reaction. The method is well suited for the synthesis of high molecular mass, monodisperse ionomers with p‐carboxylate groups situated randomly along the polystyrene chain.