CNS Team Finds Exception to Laws of Thermodynamics
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A team of researchers led by a College of Natural Sciences physics graduate student recently made the surprising discovery of what they call a “shape-recovering liquid,” which defies some long-held expectations derived from the laws of thermodynamics. The research, published in Nature Physics, details a mixture of oil, water, and magnetized particles that, when shaken, always quickly separates into what looks like the classically curvaceous lines of a Grecian urn.
“Imagine your favorite Italian salad dressing,” says Thomas Russell, Silvio O. Conte Distinguished Professor of Polymer Science and Engineering in the College of Natural Sciences and one of the paper’s senior authors. “It’s made up of oil, water, and spices, and before you pour it onto your salad, you shake it up so that all the ingredients mix.” It’s those spices, those small bits of something else, that allow water and oil, which are normally mutually exclusive, to mix. This is a process called emulsification, and is described by the laws of thermodynamics.
Emulsification underlies a vast range of technologies and applications far beyond condiments, and one day, UMass Amherst graduate student Anthony Raykh was in the lab mixing up a batch of this scientific “salad dressing” to see what he could create—only instead of spices, he was using magnetized particles of nickel, “because you can engineer all sorts of interesting materials with useful properties when a fluid contains magnetic particles,” says Raykh. He made his mixture, shook it up—“and, in a complete surprise, the mixture formed this beautiful, pristine urn-shape.” No matter how many times or how hard he shook, the urn shape always returned.
“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,” Raykh continues. No one did. But it caught the eye of Russell and David Hoagland, professor of polymer science and engineering, the paper’s other senior author and a specialist in soft materials.
The team conducted experiments and reached out to colleagues at Tufts and Syracuse universities to construct simulations. Together, the collaborative effort determined that magnetism, strong magnetism, explains the inexplicable phenomenon Raykh had discovered.
“When you look very closely at the individual nanoparticles of magnetized nickel that form the boundary between the water and oil,” says Hoagland, “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.”
Typically, particles added to an oil-and-water mixture decrease the tension at the interface between the two liquids, allowing them to mix. But in a twist, particles that are magnetized strongly enough actually increase the interfacial tension, bending the boundary between oil and water into a graceful curve.
“When you see something that shouldn’t be possible, you have to investigate,” says Russell.
While there’s no application for his novel discovery yet, Raykh is excited to see how this never-before-seen state can influence the field of soft-matter physics.
This research was funded by the U.S. National Science Foundation and the U.S. Department of Energy.
Learn more about this work: Times of India, Popular Mechanics, IFLScience, SciTechDaily, ScienceDaily, Sci.News, Phys.org, Bioengineer.org, Interesting Engineering, Greek Reporter, Science Alert, The Debrief, Earth.com, BGR.
This story was originally published by the UMass News Office.