Ion Transport Properties of Self-Assembled Polymer Electrolytes: The Role of Confinement and Interface

Ion transport properties of block copolymers with lamellar morphologies, which contain ionic liquids (ILs), were investigated. By varying the type of anion in the ILs, dissimilar substructures of lamellar microdomains were identified using different elastic scattering techniques. By decoupling the segmental motion of polymer chains from conductivity, a wide range of normalized conductivities from 0.03 to 0.6 (theoretical value of 1) were determined, depending on the type of IL. The highest conductivity was achieved when ILs were confined within ionic domains with a sharp interface, owing to the creation of less tortuous ion conduction pathways. In contrast, a high degree of intermixing of ionic and nonionic domains at the interface, because of IL incorporation, revealed a reduction by 1 order of magnitude in the conductivity. This work presents fascinating experimental insights into confinement- and interface-driven modulation of ion transport properties for polymer electrolytes and presents the future prospects for designing desired nanostructures as efficient ion conductors.