Abstract
In recent years, self-propelled molecular assemblies in non-equilibrium system have drawn much attention in viewpoint of construction of inanimate chemical machinery. We have reported self-propelled oil droplets in a water-oil-surfactant emulsion (T. Toyota, et al, J. Am. Chem. Soc. 2009, 131, 5012-5013) As we found that oil droplets of heptyloxybenzaldehyde showed self-propelled motion in about 5 min in a solution of hexadecyltrimethylammonium bromide (50 mM), we tried to control the self-propelled motion of oil droplets which interact with each other for construction of high hierarchical non-linear dynamics of oil droplets. Regarding the surface electrostatic layer of oil droplets, we added nonanoic acid (150mM), in the emulsion of heptyloxybenzaldehyde (150 mM) and hexadecyltrimethylammonium bromide (50 mM) and found that oil droplets moved autonomously and some were grouped for 3-25 s and then parted from each other. It is to be noted that the oil droplets showed such cooperative dynamics in non-equilibrium system composed of simple lipophilic and amphiphilic compounds.
