Deformation and Breakup of Micro- and Nanoparticle Stabilized Droplets in Microfluidic Extensional Flows

Mulligan, M. K. and Rothstein, J. P.. (2011) Deformation and Breakup of Micro- and Nanoparticle Stabilized Droplets in Microfluidic Extensional Flows. Langmuir, 27 (16). pp. 9760-9768.

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Using a microfluidic flow-focusing device, mono-disperse water droplets in oil were generated and their interface populated by either 1 mu m or 500 nm amine modified silica particles suspended in the water phase. The deformation and breakup of these Pickering droplets were studied in both pure extensional flow and combined extensional and shear flow at various capillary numbers using a microfluidic hyperbolic contraction. The shear resulted from droplet confinement and increased with droplet size and position along the hyperbolic contraction. Droplet deformation was found to increase with increasing confinement and capillary number. At low confinements and low capillary numbers, the droplet deformation followed the predictions of theory. For fully confined droplets, where the interface was populated by 1 mu m silica particles, the droplet deformation increased precipitously and two tails were observed to form at the rear of the droplet. These tails were similar to those seen for surfactant covered droplets. At a critical capillary number, daughter droplets were observed to stream from these tails. Due to the elasticity of the particle-laden interface, these drops did not return to a spherical shape, but were observed to buckle. Although increases in droplet deformation were observed, no tail streaming occurred for the 500 nm silica particle covered droplets over the range of capillary numbers studied.

Item Type: Article
InterNano Taxonomy: Nanomanufacturing Processes > Nanopatterning/Lithography > Microfluidic deposition
Nanoscale Objects and Nanostructured Materials > Nanoparticles
Collections: Nanomanufacturing Research Collection > Nanomanufacturing Nanoscale Science and Engineering Centers > Center for Hierarchical Manufacturing
Depositing User: Robert Stevens
Date Deposited: 03 May 2012 16:21
Last Modified: 03 May 2012 16:22

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