Home > AnnaLab Blog > Adsorption of colloidal particles to bubbles in microchannels

Adsorption of colloidal particles to bubbles in microchannels

Our paper entitled “Probing timescales for colloidal particle adsorption using slug bubbles in rectangular microchannels,” by A.P. Kotula and S.L. Anna, has been published in Soft Matter (DOI:10.1039/C2SM25970B).

The flow of long bubbles in microchannels containing a surface-active particle suspension leads to unique bubble dynamics that arise due to particle adsorption at the gas-liquid interface.

Abstract: The adsorption of particles to fluid-fluid interfaces is a key step in the generation of colloidosomes and particle-stabilized emulsions. Microfluidic channels are a promising tool for generating particle-stabilized drops and bubbles with independent control over the bubble size and the concentration of particles adsorbed at the fluid interface. In this paper, we present experimental observations of the adsorption of a nanoparticle-surfactant suspension to confined bubbles translating along a microchannel. Long bubbles exhibit a unique two-lobed shape that is linked to the adsorption of surface-active particles to the interface at a timescale comparable to the residence time in the channel. An accompanying decrease in the bubble velocity results from the added viscous drag at the bubble interface. We develop a transport model to describe the rate of particle adsorption to the interface and find good agreement between the model estimates of bubble shape changes and experimental observation. The formation of the two-lobed shape is due to a difference in the velocity between the front and rear of the bubble, which can promote bubble break-up.

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