Analytical Sciences

Surface Tension Gradient around an Alcohol Droplet Moving Spontaneously on a Water Surface

Shogo OSHIMA,* Tomonori NOMOTO,* Taro TOYOTA,**,*** and Masanori FUJINAMI*

*Department of Applied Chemistry and Biotechnology, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
**Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
***Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

The surface tension gradients in the front and rear sides of a 1-hexanol droplet exhibiting self-propelled motion were compared by a time-resolved quasi-elastic laser scattering method. The velocity of the alcohol droplet strongly correlated to the difference of the inverse of the recovery distances of the surface tensions between the front and rear sides. This result indicates that the spontaneous alcohol droplet motion is governed by an imbalance in the Marangoni convection flow, induced by an asymmetric surface tension distribution.

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