Mostafa Yourdkhani, a postdoctoral research associate in the AMS Group, and Shijia Tang, a graduate research assistant in materials science and engineering, submitted the video, which shows the formation of oil-in-water emulsion using a flow-focusing microfluidic device.
The video shows oil droplets moving from one glass capillary to another through the use of a high-speed camera (Phantom v7.3 Digital Camera) mounted on an optical microscope (Olympus IX51) in the lab of Jeff Moore, a professor of chemistry and member of the AMS Group.
The two glass capillaries are enclosed in a larger glass casing. Oil is released from the left, hitting water, and creating an emulsion composed of perfectly similar spherical objects entering the capillary on the right. The video has been magnified five times to show the objects, which are 300 to 400 microns in diameter.
“The video is beautiful because you can see how droplets are formed, and all the waves that are forming inside the droplets as the oil separates,” Yourdhkani said. “At the end, we get a lot of droplets that are exactly the same, and if you make microcapsules out of them, the microcapsules are also exactly the same.
“The advantage here is that since we are controlling the flow of fluids using microfluidics, the droplets form one at a time and, since everything from physics is the same, we can create emulsions that are exactly the same.”
The oil used in the video contains the core of a microcapsule and a polymer, as well as a solvent that can dissolve the polymer and the core. Once droplets are formed, the solvent is removed and the polymer starts to form a shell around the core, providing a core-shell structure that can be used for a variety of applications. The procedure is reported in a paper in ACS Applied Materials and Interfaces.
“The goal of the project in general is to create microcapsules that will go into coatings of oil and gas pipelines,” said Yourdkhani. “If there is any corrosion, the corrosive medium becomes acidic, and that acid will trigger the release of anti-corrosive core material to save the coating.”
“Although the method is beautiful on film, it is also a powerful tool that greatly expands the types of anti-corrosion agents and other reactive materials we can encapsulate,” said Nancy Sottos, a professor of materials science and engineering and principal investigator on the project, which is sponsored by the BP International Center for Advanced Materials (BP-ICAM).
The AMS Group was able to make microcapsules out of the polymer, cyclic poly(phthalaldehyde). Yourdhkani envisions a number of uses for the capsules.
“This concept could be applied to make capsules and beads for many purposes—for drug delivery, for example. The key benefit here is since they are all uniform size, you can have predictable behavior, or predictable release of the beneficial agents. For drug delivery, you want to have control of the capsules so that they are programmable.”
Nikon’s Small World is regarded as the leading forum for showcasing the beauty and complexity of life as seen through the light microscope. The Small World in Motion competition encompasses any movie or digital time-lapse photography taken through the microscope.