The synthesis of ionically functionalized branched polythiophenes with either carboxylic acid (anionic, P3T-COOH) or methylimidazolium (cationic, P3T-MIM) end groups is presented. Due to the large number of end groups present in the polymer, the functionalization has a major impact on the solubility of the polymers. In the case of P3T-COOH, the polymer shows a fully reversible phase transfer between organic solvents and water, depending on the ...