Issue 27, 2025

Inhibition of oscillatory motion of a camphor float due to dissolution

Abstract

To elucidate significance of nonequilibrium at an air/aqueous interface during self-propulsion of a camphor object, oscillatory motion of a self-propelled object composed of a smaller camphor disk and larger plastic disk floating on an aqueous Na2SO4 phase was investigated. Both the frequency and maximum speed of the oscillatory motion decreased with an increase in the concentration of Na2SO4 in the aqueous phase, Ci. The decrease in the frequency of the oscillatory motion is attributed to the dissolution rate of camphor in the aqueous phase as a function of Ci. The frequency of the oscillatory motion was numerically calculated as a function of the dissolution rate constant, k, and the saturated concentration of camphor in the aqueous salt solution, C0. The decrease in the maximum speed of the oscillatory motion as a function of Ci was reproduced by the difference in the surface tension (Δγ) as the driving force of motion and the friction coefficient of motion (μ) which corresponds to the viscosity of the aqueous phase. This study proposes that the nature of self-propulsion can be controlled by the dissolution into the bulk water phase as the 3D space and the nonequilibrium adsorption of energy source molecules on the interface as the 2D space.

Graphical abstract: Inhibition of oscillatory motion of a camphor float due to dissolution

Supplementary files

Article information

Article type
Paper
Submitted
04 Apr 2025
Accepted
13 Jun 2025
First published
13 Jun 2025
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2025,27, 14315-14320

Inhibition of oscillatory motion of a camphor float due to dissolution

M. Kuze, M. Tateishi, Y. Hayashi, M. Matsuo and S. Nakata, Phys. Chem. Chem. Phys., 2025, 27, 14315 DOI: 10.1039/D5CP01298H

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