Development of Anisotropically Ion and Mass-Transporting Materials through Self-Organization of Ionic Liquids

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The fabrication of functional molecular materials forming hierarchical ordered structures is one of important subjects for the next generation. Use of self-organization processes is a versatile tool for the preparation of such materials. In particular, electron and ion-transporting organic materials have attracted attention due to their potential applications in the fields of molecular devices and transportation of information and energy. Among the ion-transporting materials, we focused on ionic liquids that are organic molten salts showing high ionic conductivities. The objective in this study is to develop low-dimensionally ion-transporting materials through self-organization of ionic liquid crystals obtained by the chemical modification of imidazolium salts. Here we report on two types of anisotropic ion-transporting materials : (1)one-dimensionally (1D) ion-transporting columnar liquid crystals ; (2)two-dimensionally (2D) ion-transporting polymeric films.(1)1D ion-transporting colu … More mnar liquid crystalsWe designed and prepared fan-shaped block molecules comprising lipophilic part and imidazolium moieties. These molecules exhibited columnar liquid crystalline phases. In these structures, the tonic parts self-organized into the center of columns. The columns were macroscopically aligned parallel to the glass surface by mechanical shearing. The ionic conductivities parallel to the columnar axis were higher than those perpendicular to the axis. For the first time, anisotropic 1D ion conduction was achieved for columnar liquid crystalline materials.(2)2D ion-transporting polymeric filmsSmectic liquid crystalline imidazolium salts having polymerizable groups were prepared to obtain 2D ion-conductive mechanically stable polymeric films. These molecules in the smectic A phase spontaneously formed homeotropic monodomains on the glass surface. Self-standing polymeric films with layered nanostructures were obtained by photopolymerization of the oriented materials. They showed anisotropic 2D tonic conductivities. Less