Charged Polymers with Various Ionic Additives: Phase Behavior, Ion Clustering, and Ion Transport Properties*

Theoretical and experimental analyses of the thermodynamic properties of charged polymers have provided insights into how to control nanostructures via electrostatic interactions and improve the ionic conductivity without compromising mechanical strength, which is crucial for practical applications. In this talk, I would like to discuss methods to control the self-assembly and ion diffusion behavior of charged block copolymers by varying the type of tethered ionic moieties, local concentration of embedded ions with controlled electrostatic interactions, and nanoscale morphology. I discuss with particular emphasis on the structure–transport relationship of charged block copolymers using various ionic additives to control the phase behavior electrostatically, as well as the ion-transport properties. My group's prolonged surge and synthetic advances are pushing the frontiers of charged block copolymers to have virtually homogenous ionic domains with suppressed ion agglomeration via the nanoconfinement of closely bound ionic moieties, resulting in efficient ion conduction. I also would like to introduce the latest results of our groups on acid-tethered polymers by focusing on the design and synthesis of bifunctional polymers. Through the introduction of two types of functional moieties to precise positions of polymer backbones, ion distribution at distances of several angstroms, ion aggregation at several nanometers, and microphase separation at a few tens of nanometers could be modulated. Computational and experimental analyses have provided insights into how to improve the ionic conductivity across multiscale self-assembled structures of bifunctional polymer electrolytes without compromising mechanical strength.