Tuning Ion Dynamics and Structure via Polyzwitterionic Chemistry and Architecture in Polymer-Supported Ionic Liquid...

Zwitterionic (ZI) polymer ionogels are unusual in that they can increase both mechanical stiffness and ionic conductivity, yet how ZI chemistry and architecture control ion transport remains poorly understood. Using equilibrium and field-driven atomistic molecular dynamics, we examine how polymer chemistry (poly(MPC) vs poly(CBMA)), alkali metal identity (Li⁺ vs Na⁺), polymer loading, and ZI architecture (carbon spacer length and zwitterion orientation) regulate structure and transport in BMPTFSI-based ionogels. Nonequilibrium simulations reproduce the experimentally observed nonmonotonic conductivity with polymer content and show that conductivity trends are not set by single-ion mobilities, but by how polymer-ion interactions redistribute ion-ion correlations. Increasing ZI content shifts alkali cations from predominantly TFSI^--coordinated environments to polymer-associated states, weakening cation-anion correlations and enhancing collective transport at low to intermediate polymer loadings. This effect is stronger for Li⁺ than Na⁺ due to stronger Li⁺-ZI interactions and is most pronounced in CBMA-supported ionogels. At higher polymer fractions, conductivity decreases as ionic liquid species increasingly associate with each other and with the polymer matrix, restricting collective motion. Architectural modifications such as increasing spacer length or reversing zwitterion orientation primarily act by changing the accessibility of charged sites, weakening localized Li⁺-polymer binding while promoting association of bulkier ionic liquid ions, leading to suppressed dynamics. Together, these results frame zwitterionic polymers as coordination filters that tune conductivity by selectively decoupling alkali cations from anions while avoiding excessive immobilization of the ionic liquid.