Activation of the spontaneous motion of a nitrobenzene droplet by chlorobenzene blending

The spontaneous motion of a nitrobenzene droplet combined with iodine and potassium iodide on an aqueous phase containing a cationic surfactant (stearyltrimethylammonium chloride) was activated by the addition of a small amount of chlorobenzene into the droplet. The highest speed of droplet motion was observed when it was composed of 60% nitrobenzene and 40% chlorobenzene. To explore the factors affecting this activation, for the oil phase, the density and viscosity, the solubility of the surfactant and the interfacial tension of the oil/aqueous phase for various concentrations of nitrobenzene–chlorobenzene were evaluated. The aggregates produced at the oil/water interface were subjected to elemental and melting point analyses. These results were carefully compared with those of previous theoretical studies. The analyses revealed that the balance of the kinematic properties of the oil phase solution and the rate of the electrophilic substitution reaction is the most important factor contributing to the activation.

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► The spontaneous motion of a nitrobenzene droplet was activated by chlorobenzene addition.
► The rate of electrophilic substitution reaction is crucial.
► The kinetic properties of solutions are also important.