The influence of solvent cage structure on ionic aggregate structure, and structural morphology in polyether-ester-sulfonate copolymer ionomers.

This article focuses on the molecular dynamics (MD) simulation study of polyether-ester-sulfonate copolymer ionomers composed of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (PTMO) to elucidate their solvent cage structures, ionic aggregation, and morphological behavior. The simulations reveal that pure PEO-Na ionomers form a solvation cage via ether oxygen atoms that shield ionic interactions, resulting in weaker ionic aggregates compared to PTMO-Na ionomers, where stronger coulombic interactions lead to more pronounced ionic clustering. Increasing PEO content reduces ionic aggregation due to enhanced solvation, while raising temperature promotes ionic aggregation near the interface of PEO and PTMO microdomains, driving a thermally induced mixing tendency that improves interfacial compatibility. These findings provide microscopic insights into the interplay between solvation, ionic aggregation, and morphology, which are critical for designing single-ion conductor materials with balanced ionic conductivity and mechanical properties.