Synthesis of Ladder and Flexible Polysulfonimides Directly From Anionic Monomers: Investigating Structure-Property Convergence in Succinonitrile-Polymer Electrolyte Blends.

Insights into how permanent microporosity influences ion transport in polymer electrolytes could facilitate the design of next-generation single-ion conducting (SIC) materials. Intrinsically microporous polymers and conventional polymers are typically regarded as fundamentally distinct electrolyte platforms; direct comparisons between compositionally similar examples are lacking. Here, we introduce a strategy for the synthesis of fluorinated aryl sulfonimide-based polymers of intrinsic microporosity (FAS-PIMs) together with flexible polysulfonimide analogs of similar composition that lack permanent microporosity. Although these polymers possess fundamentally different dry-state architectures, incorporation of a common pore-filling transport medium, succinonitrile (SN), drives the two systems toward remarkably similar nanostructures with similar bulk conductivities (>10-5-10-4 S/cm at 40°C-80°C), thermomechanical properties (G' within 1-10 MPa over the temperature range of 25°C-120°C), and reprocessability. Molecular dynamics simulations and experiments suggest these unusual combinations of properties arise through different conduction mechanisms within the materials, and that sulfonimide anions are particularly advantageous for conduction in microporous matrices relative to strongly binding anions. Overall, this work introduces the first sulfonimide-based PIM, establishes a comparison between permanently microporous and transiently porous single-ion conducting polymers, and demonstrates that these two traditionally distinct electrolyte architectures can converge toward similar, useful bulk properties after incorporation of a pore-filling transport medium.