(698h) Morphology and Ion Distribution in Salt--Doped Diblock Copolymers

Lithium salt-doped block copolymer is an emerging solid polymer electrolyte material that can potentially be used as separation membrane for lithium ion batteries. By joining a glassy block (such as polystyrene) with an ion--associating block (such as poly-ethylene oxide) it offers a favorable combination of mechanical strength and ion conductivity. Understanding the ordering transition is critical to engineering material morphology and performance. The key is to resolve the difference in the dielectric response of different domains. We introduce a coarse-grained simulation model that treats Coulomb interaction explicitly and that incorporates the effects of dielectric inhomogeneity by solving the Poisson's equation explicitly. The model enables us to investigate the variation of self-assembled morphologies with the addition of salt, and to provide detailed information on ion distribution in morphologies of different symmetries. The results suggest that the oder-disorder transition temperature is raised with the addition of salt, and that the morphology of ordered phases in the ion-associating domains is strongly segregated