Tailoring Molecular Interactions in Acid-Tethered Polymers

Solid polymer electrolytes (SPEs) encounter a fatal drawback in their low ion mobility, particularly at sub-zero temperatures, owing to its close relation with the sluggish segmental

relaxation of polymer chains. In this study, we report a methodology to decouple ion mobility from polymer relaxation by precisely manipulating intermolecular interactions within SPEs.

A set of mono-functional and bi-functional polymers, poly(3-sulfonic acid styrene) (PS3S), poly(4-sulfonic acid styrene) (PS4S), poly(3-sulfonic acid-4-hydroxyl styrene) (PS-3S4H),

and poly(3- hydroxyl-4- sulfonic acid styrene) (PS-3H4s) were synthesized by aqueous reversible addition−fragmentation chain transfer (RAFT) polymerization. By incorporating

non-stoichiometric ionic liquids, we discovered that the positioning of sulfonic acid groups significantly influenced their charging behavior and the strength of electrostatic interactions.

In particular, bi-functional PS-3S4H and PS-3H4S formed intra-monomer hydrogen bonds, weakening electrostatic interactions between acid moieties and embedded ionic liquids. This

approach significantly enhanced mechanical strength while enabling efficient ion transport in SPEs, establishing a design principle for superionic SPEs through tailored molecular

interactions.