Motion modes of two self-propelled camphor boats on the surface of a surfactant-containing solution

作者：Karasawa Yuichiro; Nomoto Tomonori; Chiari Luca; Toyota Taro; Fujinami Masanori^*

来源：Journal of Colloid and Interface Science, 2018, 511: 184-192.

DOI：10.1016/j.jcis.2017.09.099

• Camphor boat
• Collective motion
• Surface tension
• Surfactant
• Marangoni flow

Hypothesis: The existence of a surface tension difference and a surface flow around self-propelled objects, such as camphor boats, has been confirmed by many studies. However, the interactions in the collective motion of several camphor boats have not been explicitly discussed. Here, a model system of two camphor boats was investigated for the first time from the viewpoint of surface tension and surface flow.
Experiments: The behavior of one fixed boat and one movable boat on a sodium dodecylsulfate aqueous solution in an oval track has been studied as a model system of two-body interactions. The surface tension around the movable boat was measured using the non-invasive, double-beam quasi-elastic laser scattering method. The Marangoni surface flow was quantitatively estimated using a mock boat in order to evaluate the net repulsive interaction between the two boats.
Findings: We succeeded in controlling the motion of the two camphor boats by varying the boat characteristics and the surfactant concentration. The balance/unbalance between the surface tension distribution and the surface flow around the boats was found to drive two different behavior modes: stationary and oscillatory. These results allow us to gain further insight into the dynamics of the interactions in the collective behavior of autonomous inanimate objects.

• 出版日期2018-2-1