Solid-State Polymer Electrolytes Based on AB3-Type Miktoarm Star Copolymers

Miktoarm star copolymers composed of three poly(ethylene oxide) (PEO) arms connected to one polystyrene (PS) chain, i.e., PS–(PEO)3, demonstrated synergistic improvements in the ionic conductivity and mechanical strength by factors of 2–30 compared to those shown by PS–PEO diblock copolymers. Entropic constraints for the chain stretching of (PEO)3 gave rise to notably reduced domain sizes of PS–(PEO)3 electrolytes, compared with the values of PS–PEO analogues. Further, the melting transition of PS–(PEO)3 with PEO molecular weight of Mn = 2 kg mol–1 was vanished with lithium salt doping at [Li]/[EO] = 0.06 under such confinements, resulting in an order of magnitude increase in the room temperature conductivity. The fact that lithium ion transport in PEO-based copolymers can be tunable by the way PEO chains are connected to hard polymers can lead to innovative designs for solid-state polymer electrolytes