Eur. Phys. J. E (2011) 34: 38
https://doi.org/10.1140/epje/i2011-11038-3

Interface dynamics under nonequilibrium conditions: From a self-propelled droplet to dynamic pattern evolution

¹ Department of Physics, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
² Spatio-Temporal Order Project, ICORP, JST (Japan Science and Technology Agency), Kyoto 606-8502, Japan
³ Nanosystems Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan

^a e-mail: rsabater@die.upv.es
^b e-mail: yoshikaw@scphys.kyoto-u.ac.jp

Received: 6 October 2010
Accepted: 1 February 2011
Published online: 18 April 2011

Abstract

In this article, we describe the instability of a contact line under nonequilibrium conditions mainly based on the results of our recent studies. Two experimental examples are presented: the selfpropelled motion of a liquid droplet and spontaneous dynamic pattern formation. For the self-propelled motion of a droplet, we introduce an experiment in which a droplet of aniline sitting on an aqueous layer moves spontaneously at an air-water interface. The spontaneous symmetry breaking of Marangoni-driven spreading causes regular motion. In a circular Petri dish, the droplet exhibits either beeline motion or circular motion. On the other hand, we show the emergence of a dynamic labyrinthine pattern caused by dewetting of a metastable thin film from the air-water interface. The contact line between the organic phase and the aqueous phase forms a unique spatio-temporal pattern characterized as a dynamic labyrinth. Motion of the contact line is controlled by diffusion processes. We propose a theoretical model to interpret essential aspects of the observed dynamic behavior.