NONLINEAR OSCILLATION AND AMEBA-LIKE MOTION IN AN OIL WATER SYSTEM/

Self-movement in an oil/water system generated by chemically driven Ma rangoni instability was studied. Repetitive changes in the interfacial tension were monitored for a two-phase system, in which the oil phase was a nitrobenzene solution of iodine and potassium iodide and the aq ueous phase contained cationic surfactant. Our findings show that inve rsion of the contact angle induced by a sudden increase in tension is essential for inducing marked acceleration in the self-motion of the o il droplet. The self-motion continues for 30-60 min and then terminate s. The movement starts again with the addition of iodine to the oil dr oplet after an induction period necessary for ''digestion'' of the nut rient, i.e., the iodine.