Protic Poly(Diallylammonium Sulfonate)s: Toward Water‐Processable Fluorine‐Free Ionic Materials

In this work, we report the synthesis of a new family of fluorine‐free protic poly(ionic liquid)s via free‐radical cyclopolymerization of protic diallylammonium monomers. Protic ionic liquid monomers based on diallylmethylammonium (DAMAH + ) and diallylammonium (DAAH 2 + ), combined with different alkyl sulfonate counter‐anions, were first prepared. Cyclopolymerization yielded a systematic series of six poly(diallylammonium) cations, five of which are newly reported here, combining two polymer backbones—poly(DAMAH + ) and the newly incorporated poly(DAAH 2 + )—with three fluorine‐free sulfonate anions, namely mesylate (MsO − ), ethylsulfonate (EsO − ), and dodecylbenzenesulfonate (DBsO − ); the previously reported poly(DAMAH + MsO − ) analogue was included for direct comparison within the same series. Systematic characterization reveals how the interplay between polymer backbone and counter‐anion governs solubility in water and organic solvents, glass transition temperatures (20–55°C), thermal stability (up to 300°C), and ionic conductivity (up to 10 −3 S cm −1 at 100°C). The combination of their physicochemical properties, electrochemical stability, and water processability highlights these polymers as a versatile fluorine‐free platform for electrochemical technologies. To demonstrate this potential, selected polymers were evaluated as water‐processable binders for LiFePO 4 cathodes, where they delivered competitive rate capability and stable electrode performance compared to PVDF. Their protic ionic character further suggests opportunities for future applications toward proton‐conducting materials. Overall, this work introduces a sustainable platform for the development of fluorine‐free ionic polymers with broad potential for electrochemical technologies.