Washington, Jan 20 : Water might not be so unique after all, with researchers pointing out that the properties which were believed to be only present in water, might also be there in some simple molecules simulated by researchers.
Conducted by chemical engineer Pablo Debenedetti from Princeton University and collaborators at three other institutions, the research found a highly simplified model molecule that behaves in much the same way as water.
While the research team's water imitator is hypothetical, it was created with computer software that is commonly used for simulating interactions between molecules.
The discovery builds on an earlier advance by the same researchers. It had previously been shown that simple molecules can show some water-like features.
In 2006, the collaborators published a paper showing that they could induce water-like peculiarities by adjusting the distance at which pairs of particles start to repel each other. Like water, their simulated substance expanded when cooled and became more slippery when pressurized. That finding led them to investigate more closely.
They decided to look at how their simulated molecule acts as a solvent - that is, how it behaves when other materials are dissolved into it - because water's behaviour as a solvent is also unique.
For the research, the team simulated the introduction of oily materials into their imitator and showed that it had the same oil-water repulsion as real water across a range of temperatures.
They also simulated dissolving oily polymers into their substance and, again, found water-like behavior. In particular, the polymers swelled not only when the "water" was heated, but also when it was super-cooled, which is one defining characteristic of real water.
In real water, these special behaviors are thought to arise from water's structure - two hydrogen atoms attached to an oxygen atom. The arrangement of electrical charges causes water molecules to twist and stick to each other in complex ways.
"The conventional wisdom is that water is unique," said Debenedetti. "And here we have a very simple model that displays behaviors that are very hard to get in anything but water. It forces you to rethink what is unique about water," he added.