Design of Chemical Systems Based on the Principle of Self-organization under Nonequilibrium

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(1) Regulation of spontaneous flow due to the principle of self-organizationWe investigated how and why a spontaneous regulated motion of an interface appears in iodide-containing nitrobenzene and water interface. The aqueous phase contains cationic surfactant. Two significant processes play roles. One is a periodic change in contact angle of the oil/water interface along the sidewall of a sample container. This is induced by a periodic ad/desorption with the chemical reaction. This wetting transition is rather fast, but the meniscus shape cannot become a stable form at the same time. Then, the hydrodynamic instability is induced for the recovery of the stability of the meniscus shape. This is the other process. As another system, we studied how and why the oil/water interface can detect a specified cation species and begins to move. For this purpose, we investigated the dependency of the spontaneous motion on the cation species. While the anionic surfactant react with all of the catio … More ns, the high reactivity under a wide range of pH's and a strong attractive interaction between the reaction products are necessary. These can be a trigger of the hydrodynamic instability.(2) Design of microstructures within fine particles due to the reaction-diffusion systemCounter-diffusion of cations and an anion in a gel-column generates a solid-solution around the center of the column. We used Ba^<2+> and Sr^<2+> (or Ca^<2+> and Mg^<2+>) as the cations and SO_4^<2-> (or CO_3^<2->) as the anion and studied the fine structure and the chemical zoning. It was concluded that the gel controls the diffusion rate of the cations, i.e., the diffusion rate of cations are sensitively dependent on the physicochemical nature of the gel and the process of gelation. Thus, the diffusion rate of a certain cation is quite different from that of the other cation. As a result of this, the gel controls the microstructure and chemical zoning of the solid solution.Physicochemical studies of the regulated spontaneous motion of fluid and the formation of the microstructures are not only necessary for the application to chemical engineering but also can be the first step for the design of chemical systems which seems to be a living matter. For example, the system moves spontaneously with an appropriate response against an environmental change and deposits solid matter with an ordered microstructure. Less