Synthesis and morphology of bifunctional polymers with controlled intramolecular interaction

Charged polymers with tailored molecular interactions have attracted significant interest as polymer electrolytes for various electrochemical systems. However, the inherent trade-off between ion transport and the glass transition temperature in these polymers make it challenging to achieve both high ionic conductivity and mechanical strength . To address this challenge, efforts have focused on developing interconnected ion channels within polymer, though this has proven non-trivial . In this study, we propose an approach to controlling morphology and ion transport in charged polymers by synthetically tuning the molecular interactions between functional groups. We design a series of bifunctional polymers through controlled radical polymerization of monomers based on phosphonated styrenes with additional functional groups. By incorporating hydroxylor dimethyl amine groups adjacent to the phosphonic acid group on the styrene ring, distinct intramonomer interactions are induced: hydroxyl groups form hydrogen bonds, while dimethyl amine groups engage in Lewis acid-base interactions. X-ray scattering experiments revealed that these polymers have distinct backbone stacking distances as well as and dissimilar arrangements of adjacent ring, depending on the functional groups. These intramonomer interactions significantly influence ion clustering behavior, resulting in tunable mechanical properties of phosphonated polymers over a broad range. We also investigate the electrolyte properties of these bifunctional polymers upon incorporating ionic liquids to better understand the structure-transport relationship in ion-channel-forming charged polymers.