Self-Motion Depending on the Physicochemical Properties of Esters as the Driving Force.

As a simple autonomous motor, the self-motion of various ester boats was investigated on water. The time variation of velocity and the duration of the motion decreased with an increase in the number of carbon atoms in the esters of acetic acid (propyl acetate, butyl acetate, and pentyl acetate). These characteristics of self-motion were qualitatively reproduced by a computer simulation based on the Newtonian motion equation that included the experimental results of surface tension depending on the concentration of ester of acetic acid and the enthalpy of evaporation. We believe that the present system regarding self-motion may be a useful tool for better understanding surface tension in chemistry in relation to physics and biology.