Phase Behavior and Ionic Conductivity of Lithium Perchlorate-Doped Polystyrene-b-poly(2-vinylpyridine) Copolymer

The phase transitions of lithium perchlorate (LiClO(4))-doped polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) were studied as a function of temperature and ion salt concentration using in situ small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Incorporation of LiClO(4) into an asymmetric, disordered PS-b-P2VP copolymer produced temperature-dependent order disorder (ODT) and order order transitions (OOTs) from spherical to lamellar microphases. The effective interaction parameter (chi(eff)) between two block components was evaluated for low molecular weight LiClO(4)-doped PS-b-P2VP in a disordered state. With increasing quantities of LiClO(4), a remarkable increase in x along with a volumetric change produced by the selective coordination of LiClO(4) to the ionophilic P2VP block led to morphological transitions from disordered (DIS) to body-centered cubic spherical (BCC) to hexagonally packed cylindrical (HEX) to lamellar (LAM) structures. We also demonstrate that the ionic conductivity in the samples quenched from the different structures is morphology-independent, while it increases with increasing salt concentration.