Thermal Properties and Ion Redistribution in Nanostructured Single-Ion Polymer Electrolyte Blends Composed of Polyanionic Miktoarm Stars

High Resolution Image Download MS PowerPoint Slide Nanostructured single-ion polymer electrolytes offer a promising strategy to decouple ionic transport from mechanical constraints, yet how nanoscale morphology governs ion partitioning and transport remains poorly understood. Here, we investigate single-ion polymer blend electrolytes composed of polyanionic miktoarm star particles dispersed in a low–molecular-weight poly(ethylene oxide) (PEO) matrix. Differential scanning calorimetry reveals composition-dependent crystallization behavior that provides insight into the distribution of Li + ions between the polyanionic particles and the oligomeric PEO phase, while polarized optical microscopy resolves the spatial organization of crystalline domains. Glass-transition analysis identifies two regimes separated at approximately 55 wt % particle loading. At high particle contents, Li + ions remain coordinated within star-rich domains, suppressing crystallization and yielding elevated T g values. At lower particle contents, formation of a continuous low–molecular-weight PEO phase coincides with a change in T g behavior, indicating redistribution of Li + ions toward the unentangled PEO matrix. Temperature-dependent ionic conductivity measurements reveal a transition in ion transport: below 55 wt % particle loading, activation energies comparable to PEO–LiTFSI reference systems indicate Li + transport dominated by vehicular diffusion in the continuous oligomeric PEO phase, whereas higher activation barriers reflect confined transport governed by ion hopping within star-rich domains. A modified Fox framework accounting for the dependence of T g on effective lithium-ion concentration captures the T g behavior across the composition range. These results show that thermal and transport signatures provide complementary evidence of morphology-driven ion partitioning and establish design principles for fast ion transport in nanostructured single-ion polymer electrolytes.