Strong Anionic Fluorene Donor-Acceptor Copolyelectrolytes from Protected Hydrophobic Precursors

Conjugated polyelectrolytes (CPEs), materials that are defined by a $$ -conjugated backbone and charged ionic functional groups, are frequently prepared through direct polymerization of charged monomer species in aqueous media. This route is, however, often accompanied by labor-intensive work-up procedures, low yields, and ultimately results in materials that are difficult to characterize. To overcome these inconveniences, in this work protection chemistry is applied on sulfonate-functionalized fluorene monomers that are polymerized under standard Suzuki polycondensation conditions to obtain protected donor-acceptor copolymers. Treatment of the organo-soluble precursors under nucleophilic conditions resulted in quantitative removal of the protecting groups, thereby exposing the strong anionic functionalities. Unlike in other studies, the conjugated backbones remained unharmed during this process: the photophysical properties of the CPEs are identical to their hydrophobic precursors.