(104c) Design of Autonomously Moving Colloidal Objects – Systematic Motion of Vesicles, Particles and Oil/Water Interface in a Homogenous Chemical Field –

The second law of thermodynamics states that all systematic motions are transformed into a random motion with molecular length scale. In biological system, however, spontaneous motions driven by chemical reaction with a molecular length scale generates a systematic motion with macroscopic scale. To study how and why the systematic motion can evolve over the hierarchy from an apparent random dynamics with smaller length scale is fascinating for designing a biomimetic chemical system. Design of autonomously moving colloidal objects is one of the methodologies that enable to understand the mechanism for the energy transduction. Moreover, the study of self-moving system may develop into various applications related to biomimetics and microfluidics. Autonomously moving colloids can demonstrate numerous significant characteristics such as transduction of chemical potential into work without heat, chemosensitive motion, and pulse-like motion with periodicities responding to the chemical environment. Here, three types of colloidal systems that exhibit autonomous motions will be discussed. Chemosensitive motion of oil/water interface that is caused by chemical Marangoni instability is the first example. The convection caused by the instability can be rectified to make one dimensional motion of a float at the interface. Second, a vesicle with rhythmic shape change is discussed. This vesicle shows a sustainable motion under a pH gradient. A vesicle that swims in a solution with specific chemical is also shown. Finally, autonomous motion of catalytic particles is discussed. The motion of homogeneous catalytic particle can be controlled by its geometry.