Physical They have announced the surprising discovery of what they call a “liquid that recovers their form”, which defies some entrenched expectations derived from the laws of thermodynamics.
The research, published in Nature Physics, details a mixture of oil, water and magnetized particles that, when stirring, is quickly separated in what looks like the classically curvilinear lines of a Greek urn.
“Imagine your favorite Italian dressing for salads,” says Thomas Russell, Professor of Policy Science and Engineering at the University of Massachusetts Amherst and one of the main authors of the article.
“It is composed of oil, water and spices, and before pouring it into the salad, it is stirred to mix all the ingredients.”
These spices, those little pieces of something, that allow water and oil, which are normally mutually exclusive, mix, a process called emulsification, described by the laws of thermodynamics.
Emulsification is the basis of a wide range of technologies and applications that go far beyond condiments, and one day, Anthony Raykh, a postgraduate student, was in the laboratory mixing a lot of this “scientific salad dressing” to see what could create; Only instead of spices, I used magnetized nickel particles, “because all kinds of interesting materials can be designed with useful properties when a fluid contains magnetic particles,” says Raykh in a statement.
He prepared his mixture, stirred it and, to his surprise, the mixture acquired a pristine form of urn. It didn’t matter how many times or how force it stirred it, the urn always returned to its original form.
“I thought: ‘What is this?’ So I toured the halls of the Department of Policy Science and Engineering, calling the doors of my teachers and asking them if they knew what was happening, ”Raykh continues. No one knew. But he caught the attention of Russell and David Hoagland, Professor of Policy Science and Engineering, the other main author of the article and Specialist in Soft Materials.
It is explained by the ‘strong’ magnetism
The team conducted experiments and contacted colleagues from Tufts and Syracuse universities to build simulations. Together, the collaborative effort determined that magnetism, the ‘strong’ magnetism, explains the inexplicable phenomenon that Raykh had discovered.
“When you carefully observe the individual magnetized nickel nanoparticles that form the border between water and oil,” says Hagland, “extremely detailed information can be obtained on how the different forms are assembled. In this case, the particles are magnetized with such force that their assembly interferes with the emulsification process, described by the laws of thermodynamics.”
Normally, particles added to a mixture of oil and water decrease the tension in the interface between both liquids, which allows its mixture. But, curiously, particles with sufficient magnetism increase interfacial tension, curvating the border between oil and water in an elegant curve.
“When you see something that should not be possible, you have to investigate it,” says Russell.
While there is still no application for its novel discovery, Raykh is excited to see how this unpublished state can influence the field of soft matter physics.