J0201-1-4 Influence of Gas Diffusion on Growth and Shrinkage of a Microbubble with Surfactant Layers

Abstract

The growth and shrinkage of surfactant-coated microbubbles are observed with a high-speed video camera. The observed bubble motion is compared with the simulation in which the dynamic surface tension and the variation of gas permeation resistance of surfactant layers are considered. The simulation is in good agreement with the experiment. It is shown that when the microbubble grows under pressure reduction, the gas diffusion from the surrounding liquid to bubble inside is suppressed by the increase of the surface tension, while it is promoted by the decrease of the gas permeation resistance. On the other hand, the bubble shrinkage due to gas diffusion after pressure increase is strongly affected by the increase of the gas permeation resistance. The variations of both the surface tension and the gas permeation resistance determine the diffusion process of microbubbles.