A Liquid That Turns Solid When Heated

Roland Piquepaille writes "There are some sure things in life, such as death and taxes. When you are heating a solid, you expect it will melt and when you're boiling water, you're pretty certain that it will turn into vapor. But what about a liquid that becomes solid when it's heated? Of course, it has already been done, for example in the chemical process of polymerization. But now, PhysicsWeb writes that a team of French physicists has discovered a law-breaking liquid that defies the rules. When you heat it between 45 and 75C, it becomes solid. But the process is fully reversible, and this is a world's premiere. When you decrease the temperature, this solid melts and turns again into a liquid. I'm not sure of the implications of such a phenomenon, but it's fascinating. Read more for essential details."

Comments

Re:Heat shield?

[novakyu]

I don't know much about physics, but could something like this be used as a heat shield of some kind? Like, where the shield is basically considered turned off when it is in the liquid state. Then when it hits a certain overload temperature, it turns to a solid and thus blocks (some of) the heat exchange?

That would probably depend on the property of the solid that forms when the solution is heated (is it a good insulator? what are its structural properties?), but I can think of one related application: temperature-controlled switch.

The solution is transparent to visible light, whereas the solid that forms is not. Since this process depends on the temperature and is reversible, it's very simple to design a circuit (using a LED and phototransistor or some sort of photo-detector) that works as temperature-dependent switch. From what the article says,

The temperature at which it becomes a solid falls as the concentration of CD increases.

it should be possible to tweak the turn-on temperature to a degree.

But then, this is not anything new--as far as dependence on temperature goes, there are many other materials that are probably more reliable (the only thing novel about this would be that its dependence is backward.)

Back to the topic, yeah, it can probably be used as heat shield in a limited capacity: i.e. if it turns out that the liquid is transparent to infrared radiation while the solid isn't, this can be used as natural temperature-controlled infrared radiation shield (but of course, it will still be subject to heating due to other methods, like...conduction via the solid itself, unless the resulting solid turns out to be similar to styroform).

Re:Application: Construction of Skyscrapers

[wash23]

It most certainly would melt again after 75C; it's just a hydrogen-bonded organic solid at that point, and hydrogen bonds are weak and only partially-covalent and would easily melt at moderate temperatures.