Designing both conductive and structural components into ion transport membranes is important for improved electrolytes for lithium ion batteries and other uses. We have synthesized block copolymers by ring opening metathesis polymerization based on an oxynorbornenedicarboximide backbone structure with an oligomeric ethylene oxide sidechain in one block and a phenyl side group in the other. The homopolymer of this ion soluble block has a measured conductivity of ~1x10<sup>-4 </sup>S/cm at 80 °C. The morphologies of thin film samples of the copolymers have been studied using atomic force microscopy (AFM) and SAXS both neat and with added salt. The block polymers with added salt order well, especially with the use of solvent vapor annealing, and produce dominantly cylinder and lamellar morphologies. The range of block copolymer compositions with lamellar structure appears to widen with added salt. Both photo-induced force microscopy (PiFM) and viscoelastic mapping mode (AM-FM) AFM techniques have been used to establish the identity of topographic AFM domains by chemical composition and relative modulus, respectively. Ion dynamics in block copolymer thin films were also studied with time-resolved electrostatic force microscopy (trEFM) and demonstrate the measurement of ion motion in the ion conductive domains at the nanometer length scale.

Morphology and ion dynamics in oligomeric ethylene oxide functionalized block copolymer electrolytes

2019 Spring National Meeting

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