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Scientists have a very good understanding of how liquids interact with each other. For example, it is known that when you mix oil and water, they will resist coming together or remaining together. This can be overcome by using an emulsifier that allows them to combine. All of this (and much, much more) is part of the laws of thermodynamics, which are scientific ‘laws’ that help to explain a lot of what is seen around us.
So, when Anthony Raykh was experimenting with various non-mixing liquids, it is an understatement to say that he was surprised when they did not behave as expected. Raykh is a graduate student at UMass Amherst, and at the time, he was using magnetized particles of nickel to see how they would react. In the study, published in Nature Physics, it is explained what happened after he shook the mixture up:
“…and, in a complete surprise, the mixture formed this beautiful, pristine urn-shape.”
Sometimes weird and unexpected things happen with experiments, which is why you have to conduct them multiple times. So, he shook the liquid up again, only to see that the urn-shape returned. After doing this multiple times and he couldn’t explain why it was happening, he went to ask his professors. He explains in a statement:
“I thought ‘what is this thing?’ So, I walked up and down the halls of the Polymer Science and Engineering Department, knocking on my professors’ doors, asking them if they knew what was going on.”
None of them knew why the liquid would behave like this. To see a comparison between what would be expected and what they saw, check out this brief video:
Two of the professors were sufficiently intrigued that they contacted their colleagues at Tufts and Syracuse universities to see if they had any idea about what was going on. They didn’t, so the group started looking more closely.
David Hoagland is a professor of polymer science and engineering at UMass Amherst, explains what they saw upon closer inspection:
“When you look very closely at the individual nanoparticles of magnetized nickel that form the boundary between the water and oil, you can get extremely detailed information on how different forms assemble. In this case, the particles are magnetized strongly enough that their assembly interferes with the process of emulsification, which the laws of thermodynamics describe.”
In the paper, they write about what they saw and their potential explanation:
Rather than promoting emulsification, interfacially active magnetic particles serve to eliminate emulsification entirely due to long-lived heterogeneities imposed on the liquid interfaces by in-plane magnetic particle interactions. The energies of these interactions are large, attractive and directional (dependent on the interparticle orientation), so the stabilization occurred concurrently with an increase in the interfacial tension. The dipolar anisotropy in magnetic interactions creates a string-like particle surface network with openings large enough to enable facile liquid transfer between contacting droplets. The particles thereby bolster the equilibration and re-equilibration of structured liquid interfaces, as evidenced by the urn-shaped phase that formed in a cylindrical vessel. Only the wetting conditions of the liquid surface and the vessel walls affected the shape.”
While very interesting, there are not currently any known uses for this type of finding.
It has never been seen before, so there could be applications in soft-matter physics, but more research will be needed to fully understand its potential.
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