Water can be separated into 2 different liquids. We’re getting closer to knowing why: ScienceAlert

The dazzling beauty of snowflakes is proof that water can take amazing shapes below freezing.

Under pressure, H’s graceful dance2O molecules twist into weird things at ultracold temperatures, actually tying themselves into knots to avoid turning into ice.

The researchers, from the University of Birmingham, UK, and the University of Rome, Italy, examined the behavior of molecules in pressurized liquid water that normally causes it to crystallize.

Based on a new method of modeling the behavior of water as a suspension of particles, they identified key features of two distinct liquid states; one “topologically complex” connected in a pretzel-like overhand knot, and the other with a lower density connected in the form of simpler rings.

University of Birmingham chemist Dwaipayan Chakrabarti said: “This colloidal model of water provides a magnifying glass for molecular water, allowing us to unlock the water’s secrets about the two-liquid story.”

theory Developed in the 1990s hints at molecular interactions that may occur when water is present too cold – Cool to a temperature below its typical freezing point without freezing.

For years, scientists have pushed the limits of cooling water without turning it into a solid state, eventually managing to keep it in chaotic temperatures at an extremely cold -263 degrees Celsius (-441 degrees Fahrenheit) without it. In a liquid state, it turns into ice for a moment.

As far as progress has been in showing these states in the lab, scientists are still trying to figure out what supercooled liquids look like without heat.

Clearly, at the critical point, the polar attraction between water molecules competing with each other outweighs the thermodynamic hum of dangling particles. With no elbow room to push into the crystalline form, the molecule needs to find other comfortable configurations.

With so many factors at play, researchers often try to simplify what they can do and focus on the variables that matter. In this case, thinking of water “clumps” as larger particles dissolved in a liquid helps to better understand the transition from one arrangement to another.

Computer models based on this idea point to subtle changes between the water pushing apart, and the form made up of particles that are more tightly packed together in a denser form.

Interestingly, the shape or topology of molecular interactions in this aquatic landscape also looks quite different, with molecules entangled in intricate webs when squeezed together or in simpler forms when they are separated. Appear.

“In this work, we present for the first time the idea of ​​a liquid-liquid phase transition based on the idea of ​​network entanglement,” says condensed matter physicist Francesco Sciortino of the University of Rome.

“I believe this work will inspire novel theoretical modeling based on topological concepts.”

This strange cyberspace of entangled particles is ripe for exploration. While not entirely different from long-chain covalently bonded molecules, such knots are short-lived, exchanging members as the liquid environment changes.

Given their entangled interactions, the properties of liquid water found in high-pressure, low-temperature environments should be quite different from anything we’ve found wobbling on Earth’s surface.

Learning more about the topological behavior of not just water under these conditions, but that of other liquids, could give us insights into material activity in extreme or inaccessible environments, such as the depths of distant planets.

“Dream how beautiful it would be if we could look inside the liquid and watch the dance of the water molecules, the way they flicker and the way they exchange partners, reorganize the hydrogen bond network,” Sciortino said.

“The realization of our proposed hydrocolloid model could make this dream a reality.”

This study was published in physical physics.

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